title: Francis II of France

text: Francis II had a brief reign. He became king as an inexperienced teenager, at a time when the kingdom was struggling with religious troubles. Historians agree that Francis II was fragile, both physically and psychologically, and his frail health led to his early death. The question of whether his marriage was consummated or not remains unanswered.


title: Francis II of France

text: Francis is portrayed by Toby Regbo in the CW show "Reign", by Richard Denning in Mary, Queen of Scots (1971 film), by Sebastian Stragiotti-Axanciuc in Mary, Queen of Scots (2013 film), and by George Jaques in "The Serpent Queen".


title: Tiger I

text: The Tiger I () was a German heavy tank of World War II that operated beginning in 1942 in Africa and in the Soviet Union, usually in independent heavy tank battalions. It gave the German Army its first armoured fighting vehicle that mounted the 8.8 cm KwK 36 gun (derived from the 8.8 cm Flak 36). 1,347 were built between August 1942 and August 1944. After August 1944, production of the Tiger I was phased out in favour of the Tiger II.


title: Tiger I

text: While the Tiger I has been called an outstanding design for its time, it has also been called overengineered, using expensive materials and labour-intensive production methods. In the early period Tiger was prone to certain types of track failures and breakdowns and was in general limited in range by its high fuel consumption. It was expensive to maintain, but generally mechanically reliable. It was difficult to transport and vulnerable to immobilisation when mud, ice, and snow froze between its overlapping and interleaved "Schachtellaufwerk"-pattern road wheels, often jamming them solid. This was a problem on the Eastern Front in the muddy "rasputitsa" season and during periods of extreme cold.


title: Tiger I

text: The tank was given its nickname "Tiger" by Ferdinand Porsche, and the Roman numeral was added after the Tiger II entered production. The initial designation was "Panzerkampfwagen VI Ausführung H" (literally "armoured combat vehicle VI version H", abbreviated "PzKpfw VI Ausf. H") where 'H' denoted Henschel as the designer/manufacturer. It was classified with ordnance inventory designation "Sd.Kfz. 182". The tank was later re-designated as "PzKpfw VI Ausf. E" in March 1943, with ordnance inventory designation "Sd.Kfz. 181".


title: Tiger I

text: Today, only seven Tiger I tanks survive in museums and private collections worldwide. , Tiger 131 (captured during the North Africa Campaign) at the UK's Tank Museum is the only example restored to running order.


title: Tiger I

text: Henschel & Sohn began the development of a large tank design in January 1937 when the "Waffenamt" requested Henschel to develop a "Durchbruchwagen" ("breakthrough vehicle") in the 30–33 tonne range. Only one prototype hull was ever built and it was never fitted with a turret. The "Durchbruchwagen" I's general shape and suspension resembled the Panzer III, while the turret resembled the early Panzer IV C turret with the short-barrelled 7.5 cm L/24 cannon.


title: Tiger I

text: Before "Durchbruchwagen" I was completed, a request was issued for a heavier 30-tonne class vehicle with thicker armour, the "Durchbruchwagen" II, which would have had 50 mm (2 in) of frontal armour and mounted a Panzer IV turret with a short-barrelled (24 calibres long) 7.5 cm KwK 37 gun. The overall weight would have been 36  tonnes. Only one hull was built and no turret was fitted. Further development of the "Durchbruchwagen" was dropped in 1938 in favour of the larger and better-armoured VK 30.01 (H) and VK 36.01 (H) designs. Both the "Durchbruchwagen" I and II prototype hulls were used as test vehicles until 1941.


title: Tiger I

text: The VK 30.01 (H) medium tank and the VK 36.01 (H) heavy tank designs pioneered the use of the complex "Schachtellaufwerk" track suspension system of torsion bar-sprung, overlapped and interleaved main road wheels for tank use. This concept was already common on German half-tracks such as the Sd.Kfz. 7. The VK 30.01 (H) was intended to mount a low-velocity 7.5 cm L/24 infantry support gun, a 7.5 cm L/40 dual-purpose anti-tank gun, or a 10.5 cm L/28 field gun in a Krupp turret. Overall weight was to be 33 tonnes. The armour was designed to be 50 mm on frontal surfaces and 30 mm on the side surfaces. Four prototype hulls were completed for testing. Two of these were later modified to build the "Sturer Emil" (12.8 cm "Selbstfahrlafette" L/61) self-propelled anti-tank gun.


title: Tiger I

text: The VK 36.01 (H) was intended to weigh 40 tonnes, with 100 mm (4 in) of armour on front surfaces, 80 mm on turret sides and 60 mm on the hull sides. The VK 36.01 (H) was intended to carry a 7.5 cm L/24, or a 7.5 cm L/43, or a 7.5 cm L/70, or a 12.8 cm L/28 cannon in a Krupp turret that looked similar to an enlarged Panzer IV Ausf. C turret. The hull for one prototype was built, followed later by five more. The six turrets built were never fitted and were used as part of the Atlantic Wall. The VK 36.01 (H) project was discontinued in early 1942 in favour of the VK 45.01 project.


title: Tiger I

text: Combat experience against the French SOMUA S35 cavalry tank and Char B1 heavy tank, and the British Matilda II infantry tanks during the Battle of France in June 1940 showed that the German Army needed better armed and armoured tanks.


title: Tiger I

text: On 26 May 1941, Henschel and Ferdinand Porsche were asked to submit designs for a 45-tonne heavy tank, to be ready by June 1942. Porsche worked on an updated version of their VK 30.01 (P) Leopard tank prototype while Henschel worked on an improved VK 36.01 (H) tank. Henschel built two prototypes: a VK 45.01 (H) H1 with an 8.8 cm L/56 cannon, and a VK 45.01 (H) H2 with a 7.5 cm L/70 cannon.


title: Tiger I

text: On 22 June 1941, Germany launched Operation Barbarossa, the invasion of the Soviet Union. The Germans were encountering large numbers of Soviet T-34 medium and KV-1 heavy tanks, that were surviving the german attack. According to Henschel designer Erwin Aders: "There was great consternation when it was discovered that the Soviet tanks were superior to anything available to the Heer."


title: Tiger I

text: Weight increase to 45 tonnes and an increase in gun calibre to 8.8 cm were ordered. The due date for the new prototypes was set for 20 April 1942, Adolf Hitler's 53rd birthday. Unlike the Panther tank, the designs did not incorporate sloped armour.


title: Tiger I

text: Porsche and Henschel submitted prototype designs, each making use of the Krupp-designed turret. They were demonstrated at Rastenburg in front of Hitler. The Henschel design was accepted, mainly because the Porsche VK 4501 (P) prototype design used a troubled petrol-electric transmission system which needed large quantities of copper for the manufacture of its electrical drivetrain components, a strategic war material of which Germany had limited supplies with acceptable electrical properties for such uses. Production of the "Panzerkampfwagen" VI "Ausf." H began in August 1942. Expecting an order for his tank, Porsche built 100 chassis. After the contract was awarded to Henschel, they were used for a new turretless, casemate-style tank destroyer; 91 hulls were converted into the "Panzerjäger" Tiger (P) in early 1943.


title: Tiger I

text: The Tiger was still at the prototype stage when it was first hurried into service, and therefore changes both large and small were made throughout the production run. A redesigned turret with a lower cupola was the most significant change. The river-fording submersion capability and an external air-filtration system were dropped to cut costs.


title: Tiger I

text: The Tiger differed from earlier German tanks principally in its design philosophy. Its predecessors balanced mobility, armour and firepower and were sometimes outgunned by their opponents.


title: Tiger I

text: While heavy, this tank was not slower than the best of its opponents. However, at over 50 tonnes dead weight, the suspension, gearboxes, and other such items had clearly reached their design limits and breakdowns were frequent if regular maintenance was not undertaken.


title: Tiger I

text: Although the general design and layout were broadly similar to the previous medium tank, the Panzer IV, the Tiger weighed more than twice as much. This was due to its substantially thicker armour, the larger main gun, greater volume of fuel and ammunition storage, larger engine, and a more solidly built transmission and suspension.


title: Tiger I

text: The Tiger I had frontal hull armour thick, frontal turret of and gun mantlet with a varying thickness of to . The Tiger had thick hull side plates and 80 mm armour on the side superstructure/sponsons, while turret sides and rear were 80 mm. The top and bottom armour was thick; from March 1944, the turret roof was thickened to . Armour plates were mostly flat, with interlocking construction. This flat construction encouraged angling the Tiger hull roughly 30-45° when firing in order to increase effective thickness. The armour joints were stepped and welded rather than riveted, and were made of maraging steel.


title: Tiger I

text: The 56-calibre long 8.8 cm KwK 36 was chosen for the Tiger. A combination of a flat trajectory from the high muzzle velocity and precision from the Leitz "Turmzielfernrohr" TZF 9b sight (later replaced by the monocular TZF 9c) made it very accurate. In British wartime firing trials, five successive hits were scored on a target at a range of . Compared with the other contemporary German tank guns, the 8.8 cm KwK 36 had superior penetration to the 7.5 cm KwK 40 on the Sturmgeschütz III and Panzer IV but inferior to the 7.5 cm KwK 42 on the Panther tank under ranges of 2,500 metres. At greater ranges, the 8.8 cm KwK 36 was superior in penetration and accuracy. The gun took around 10.9 seconds to reload.


title: Tiger I

text: The ammunition for the Tiger had electrically fired primers. Four types of ammunition were available but not all were fully available; the PzGr 40 shell used tungsten, which was in short supply as the war progressed.


title: Tiger I

text: The rear of the tank held an engine compartment flanked by two separate rear compartments each containing a fuel tank and radiator. The Germans had not developed an adequate diesel engine, so a petrol (gasoline) powerplant had to be used instead. The original engine utilized was a 21.35-litre (1303 cu.in.) 12-cylinder Maybach HL210 P45 developing 485 kW (650 hp) at 3,000 rpm and a top speed of 38km (24mph.) It was determined to be underpowered for the vehicle from the 251st Tiger onwards. It was replaced by the upgraded HL 230 P45, a 23.095 litre (1409 cu.in.) engine developing 521 kW (700 hp) at 3,000 rpm. The main difference between these engines was that the original Maybach HL 210 used an aluminium engine block while the Maybach HL 230 used a cast-iron engine block. The cast-iron block allowed for larger cylinders (and thus, greater displacement) which increased the power output to 521 kW (700 hp). The engine was in V-form, with two cylinder banks set at 60 degrees. An inertia starter was mounted on its right side, driven via chain gears through a port in the rear wall. The engine could be lifted out through a hatch on the rear hull roof. In comparison to other V12 and various vee-form gasoline engines used for tanks, the eventual HL 230 engine was nearly four litres smaller in displacement than the Allied British Rolls-Royce Meteor V12 AFV power plant, itself adapted from the RR Merlin but de-rated to 448 kW (600 hp) power output; and the American Ford-designed precursor V12 to its Ford GAA V-8 AFV engine of 18 litre displacement, which in its original V12 form would have had the same 27 litre displacement as the Meteor.


title: Tiger I

text: The engine drove the front sprockets through a drivetrain connecting to a transmission in the front portion of the lower hull; the front sprockets had to be mounted relatively low as a result. The Krupp-designed 11-tonne turret had a hydraulic motor whose pump was powered by mechanical drive from the engine. A full rotation took about a minute.


title: Tiger I

text: Another new feature was the Maybach-Olvar hydraulically controlled semi-automatic pre-selector gearbox. The extreme weight of the tank also required a new steering system. Germany's Argus Motoren, where Hermann Klaue had invented a ring brake in 1940, supplied them for the Arado Ar 96 and also supplied the 55 cm disc. Klaue was acknowledged in the patent application that he had improved, it can even be traced back to British designs dating to 1904. It is unclear whether Klaue's patent ring brake was utilised in the Tiger brake design.


title: Tiger I

text: The clutch-and-brake system, typical for lighter vehicles, was retained only for emergencies. Normally, steering depended on a double differential, Henschel's development of the British Merritt-Brown system first encountered in the Churchill tank. The vehicle had an eight-speed gearbox, and the steering offered two fixed radii of turns on each gear, thus the Tiger had sixteen different radii of turn. In first gear, at a speed of a few km/h, the minimal turning radius was . In neutral gear, the tracks could be turned in opposite directions, so the Tiger I pivoted in place. There was a steering wheel instead of either a tiller – or, as most tanks had at that time, twin braking levers – making the Tiger I's steering system easy to use, and ahead of its time.


title: Tiger I

text: Powered turret traverse was provided by the variable speed Boehringer-Sturm L4 hydraulic motor, which was driven from the main engine by a secondary drive shaft. On early production versions of the Tiger maximum turret traverse was limited to 6º/second, whilst on later versions a selectable high speed traverse gear was added. Thus the turret could be rotated 360 degrees at up to 6º/second in low gear independent of engine rpm (same as on early production versions), or up to 19º/second with the high speed setting and engine at 2000 rpm, and at over 36º/second at the maximum allowable engine speed of 3000 rpm. The direction and speed of traverse was controlled by the gunner through foot pedals, the speed of traverse corresponding to the level of depression the gunner applied to the foot pedal. This system allowed for very precise control of powered traverse, a light touch on the pedal resulting in a minimum traverse speed of 0.1 deg/sec (360 degrees in 60 min), unlike in most other tanks of the time (e.g. US M4 Sherman or Soviet T-34) this allowed for fine laying of the gun without the gunner needing to use his traverse handwheel.


title: Tiger I

text: The suspension used sixteen torsion bars, with eight suspension arms per side. To save space, the swing arms were leading on one side and trailing on the other side, this is called an H suspension setup. There were three road wheels (one of them double, closest to the track's centre) on each arm, in a so-called "Schachtellaufwerk" overlapping and interleaved arrangement, similar to that pioneered on German half-tracked military vehicles of the pre-World War II era, with the Tiger I being the first all-tracked German AFV built in quantity to use such a road wheel arrangement. The wheels had a diameter of in the "Schachtellaufwerk" arrangement for the Tiger I's suspension, providing a high uniform distribution of the load onto the track, at the cost of increased maintenance.


title: Tiger I

text: Removing an inner wheel that had lost its solid rubber tire (a common occurrence) required the removal of up to nine other wheels first. During the rainy period that brought on the autumn "rasputitsa" mud season and onwards into the winter conditions on the Eastern front, the roadwheels of a "Schachtellaufwerk"-equipped vehicle could also become packed with mud or snow that could then freeze. Presumably, German engineers, based on the experience of the half-tracks, felt that the improvement in off-road performance, track and wheel life, mobility with wheels missing or damaged, plus additional protection from enemy fire was worth the maintenance difficulties of a complex system vulnerable to mud and ice. This approach was carried on, in various forms, to the Panther and the non-interleaved wheel design for the Tiger II. Eventually, a new 80 cm diameter 'steel' wheel design, closely resembling those on the Tiger II, with an internally sprung steel-rim tire was substituted, and which like the Tiger II, were only overlapped and not interleaved.


title: Tiger I

text: To support the considerable weight of the Tiger, the tracks were wide. To meet rail-freight size restrictions, the outermost roadwheel on each axle (16 total) could be unbolted from a flange and narrower wide 'transport' tracks ("Verladeketten") installed. The track replacement and wheel removal took 30 minutes for each side of the tank. However, in service, Tigers were frequently transported by rail with their combat tracks fitted, as long as the train crew knew there were no narrow tunnels or other obstructions on the route that would prevent an oversized load from passing, despite this practice being strictly forbidden.


title: Tiger I

text: The Tiger tank's combat weight of 56 tons was often too heavy for small bridges which had 35 ton weight limits, so it was designed to ford bodies of water up to deep. This required unusual mechanisms for ventilation and cooling when underwater. At least 30 minutes of set-up time was required, with the turret and gun being locked in the forward position, and a large snorkel tube raised at the rear. An inflatable doughnut-shaped ring sealed the turret ring. The two rear compartments (each containing a fuel tank, radiator and fans) were floodable. However, this ability was found to be of limited practical value for its high cost and was removed from production lines in August 1943. As a result, only the first 495 units were fitted with this deep fording system; all later models were capable of fording water only two metres deep.


title: Tiger I

text: The internal layout was typical of German tanks. Forward was an open crew compartment, with the driver and radio-operator seated at the front on either side of the gearbox. Behind them the turret floor was surrounded by panels forming a continuous level surface. This helped the loader to retrieve the ammunition, which was mostly stowed above the tracks. Three men were seated in the turret; the loader to the right of the gun facing to the rear, the gunner to the left of the gun, and the commander behind him. There was also a folding seat on the right for the loader. The turret had a full circular floor and 157 cm headroom. Early versions of the Tiger I's turret included two pistol ports; however, one of these was replaced with a loader escape hatch and the other deleted from later designs.


title: Tiger I

text: Post-war testing by the Allies found the tank to be uncomfortable and spartan. For example, the gunner suffered from clumsy controls and a cramped area. This was in contrast to German crews who found them to be spacious and comfortable.


title: Tiger I

text: A substantial problem with the Tiger was that its production required considerable resources in terms of manpower and material, which led to it being expensive: the Tiger I cost over twice as much as a Panzer IV and four times as much as a StuG III assault gun. Partly because of their high cost, only 1,347 Tiger I and 492 Tiger II tanks were produced. The closest counterpart to the Tiger from the United States was the M26 Pershing (around 200 deployed to the European Theater of Operations (ETO) during the war) and the IS-2 from the USSR (about 3,800 built during the conflict).


title: Tiger I

text: From a technical point of view it was better suited compared to its contemporaries. Despite the low number produced, shortages in qualified crew and the considerable fuel requirement in a context of ever shrinking resources, Tiger tanks had a large impact in the war with Tigers (including Tiger IIs) destroying at least 10,300 enemy tanks, and 11,380 AT guns and artillery pieces in WW2. This was achieved for the loss of 1,725 Tigers (including large numbers of operational and strategic losses, i.e. abandoned, broken down, etc.).


title: Tiger I

text: Production of the Tiger I began in August 1942 at the factory of Henschel und Sohn in Kassel, initially at a rate of 25 per month and peaking in April 1944 at 104 per month. An official document of the time stated that the first Tiger I was completed on 4 August. 1,355 had been built by August 1944, when production ceased. Deployed Tiger I's peaked at 671 on 1 July 1944. It took about twice as long to build a Tiger I as another German tank of the period. When the improved Tiger II began production in January 1944, the Tiger I was soon phased out.


title: Tiger I

text: In 1943, Japan bought several specimens of German tank designs for study. A single Tiger I was apparently purchased, along with a Panther and two Panzer IIIs, but only the Panzer IIIs were actually delivered. The undelivered Tiger was loaned to the German Wehrmacht by the Japanese government.


title: Tiger I

text: Many modifications were introduced during the production run to improve automotive performance, firepower and protection. Simplification of the design was implemented, along with cuts due to raw material shortages. In 1942 alone, at least six revisions were made, starting with the removal of the "Vorpanzer" (frontal armour shield) from the pre-production models in April. In May, mudguards bolted onto the side of the pre-production run were added, while removable mudguards saw full incorporation in September. Smoke discharge canisters, three on each side of the turret, were added in August 1942. In later years, similar changes and updates were added, such as the addition of Zimmerit (a non-magnetic anti-mine coating), in late 1943. Due to slow production rates at the factories, incorporation of the new modifications could take several months.


title: Tiger I

text: The humorous and somewhat racy crew manual, the "Tigerfibel", was the first of its kind for the German Army and its success resulted in more unorthodox manuals that attempted to emulate its style.


title: Tiger I

text: Among other variants of the Tiger, a heavily armoured casemate self-propelled rocket projector, today commonly known as the "Sturmtiger", was built, which mounted a 38 cm/15in rocket launcher. A tank recovery version of the Porsche Tiger I (Bergetiger), and one Porsche Tiger I, was issued to the 654th Heavy Tank Destroyer Battalion, which was equipped with the Ferdinand/Elefant.


title: Tiger I

text: In Italy, a demolition carrier version of the Tiger I without a main gun was built by maintenance crews in an effort to find a way to clear minefields. It is often misidentified as a "BergeTiger" recovery vehicle. As many as three may have been built. It carried a demolition charge on a small crane on the turret in place of the main gun. It was to move up to a minefield and drop the charge, back away, and then set the charge off to clear the minefield. There is no verification of any being used in combat.


title: Tiger I

text: Another variant was the Fahrschulpanzer VI Tiger tanks (driving school Tiger tanks). These tanks were Tigers with modified engines to run on either compressed Towngas gas (Stadtgas System) or wood gas (Holzgas System). This was due to shortages in fuel supply. They used a mixture of turreted and turretless hulls. They were used to train Tiger tank crews, and were not used in combat.


title: Tiger I

text: Hitler's order, dated 27 February 1944, abolished the designation "Panzerkampfwagen VI" and ratified "Panzerkampfwagen" Tiger "Ausf." E, which was the official designation until the end of the war. For common use it was frequently shortened to "Tiger".


title: Tiger I

text: A report prepared by the "Waffenamt-Prüfwesen" 1 gave the calculated probability of perforation at range, on which various adversaries would be defeated reliably at a side angle of 30 degrees to the incoming round.


title: Tiger I

text: The "Wa Prüf" report estimated that the Tiger's 88 mm gun would be capable of penetrating the differential case of an American M4 Sherman from and the turret front from , but the Tiger's 88 mm gun would not penetrate the upper glacis plate at any range assuming a side angle of 30 deg. The M4 Sherman's 75 mm gun would not penetrate the Tiger frontally at any range, and needed to be within 100 m to achieve a side penetration against the 80 mm upper hull superstructure. The Sherman's upgraded 76 mm gun might penetrate the Tiger's driver's front plate from 600 m, the nose from 400 m and the turret front from 700 m. The M3 90 mm cannon used as a towed anti-aircraft and anti-tank gun, and later mounted in the M36 tank destroyer and finally the late-war M26 Pershing, could penetrate the Tiger's front plate at a range of 1,000 m using standard ammunition, and from beyond 2,000 m when using HVAP.


title: Tiger I

text: Soviet ground trial testing conducted in May 1943 determined that the 8.8 cm KwK 36 gun could pierce the T-34/76 frontal beam nose from 1500 m, and the front hull from 1500 m. A hit to the driver's hatch would force it to collapse inwards and break apart. According to the Wa Prüf 1 report, the Soviet T-34-85's upper glacis and turret front armour would be defeated between at a side angle of 30 deg, while the T-34's 85 mm gun was estimated to penetrate the front of a Tiger between at a side angle of 30 degrees to the incoming round. Soviet testing showed that the 85 mm gun could penetrate the front of a Tiger from with no side angle


title: Tiger I

text: At a side impact angle of 30 deg the 120 mm hull armour of the Soviet IS-2 model 1943 would be defeated between at the driver's front plate and nose. The IS-2's 122 mm gun could penetrate the Tiger's front armour from between , depending on the impact angle. However, according to Steven Zaloga, the IS-2 and Tiger I could each knock the other out in normal combat distances below 1,000 m. At longer ranges, the performance of each respective tank against each other was dependent on the crew and the combat situation.


title: Tiger I

text: The British Churchill Mk IV was vulnerable to the Tiger from the front at between at a 30 deg side angle, its strongest point being the nose and its weakest the turret. According to an STT document dated April 1944, it was estimated that the British 17-pounder, as used on the Sherman Firefly, firing its normal APCBC ammunition, would penetrate the turret front and driver's visor plate of the Tiger out to .


title: Tiger I

text: When engaging targets, Tiger crews were encouraged to angle the hull to the 10:30 or 1:30 clock position (45 degrees) relative to the target, an orientation referred to as the "Mahlzeit Stellung". This would maximize the effective front hull armour to 180mm and side hull to 140mm, making the Tiger impervious to any Allied gun up to 152 mm. The Tiger's lack of slope for its armour made angling the hull by manual means simple and effective, and unlike the lighter Panzer IV and Panther tanks, the Tiger's thick side armour gave a degree of confidence of immunity from flank attacks. The tank was also immune to Soviet anti-tank rifle fire to the sides and rear. Its large calibre 8.8 cm provided superior fragmentation and high explosive content over the 7.5 cm KwK 42 gun. Therefore, comparing the Tiger with the Panther, for supporting the infantry and destroying fortifications, the Tiger offered superior firepower. It was also key to dealing with towed anti-tank guns, according to German tank commander Otto Carius:


title: Tiger I

text: Eager to make use of the powerful new weapon, Hitler ordered the vehicle be pressed into service months earlier than had been planned. A platoon of four Tigers went into action on 23 September 1942 near Leningrad. Operating in swampy, forested terrain, their movement was largely confined to roads and tracks, making defence against them far easier. Many of these early models were plagued by problems with the transmission, which had difficulty handling the great weight of the vehicle if pushed too hard. It took time for drivers to learn how to avoid overtaxing the engine and transmission, and many broke down. The most significant event from this engagement was that one of the Tigers became stuck in swampy ground and had to be abandoned. Captured largely intact, it enabled the Soviets to study the design and prepare countermeasures.


title: Tiger I

text: The 503rd Heavy Panzer Battalion was deployed to the Don Front in the autumn of 1942, but arrived too late to participate in Operation Winter Storm, the attempt to relieve Stalingrad. It was subsequently engaged in heavy defensive fighting in the Rostov-on-Don and adjacent sectors in January and February 1943.


title: Tiger I

text: In the North African Campaign, the Tiger I first saw action during the Tunisian Campaign on 1 December 1942 east of Tebourba, when three Tigers attacked an olive grove 5 km west of Djedeida. The thick olive grove made visibility very limited and enemy tanks were engaged at close range. The Tigers were hit by a number of M3 Lee tanks firing at a range of 80 to 100 metres. Two of the Lees were knocked out in this action, and the Tiger tanks provided protection from enemy fire; which greatly increased the crews trust in the quality of the armour. The first loss to an Allied gun was on 20 January 1943 near Robaa, when a battery of the British 72nd Anti-Tank Regiment knocked out a Tiger with their 6-pounder (57 mm) anti-tank guns. Seven Tigers were immobilised by mines during the failed attack on Béja during Operation Ochsenkopf at the end of February.


title: Tiger I

text: In July 1943, two heavy tank battalions (503rd and 505th) took part in Operation Citadel resulting in the Battle of Kursk with one battalion each on the northern (505th) and southern (503rd) flanks of the Kursk salient the operation was designed to encircle. However, the operation failed and the Germans were again put on the defensive. The resulting withdrawal led to the loss of many broken-down Tigers which were left un-recovered with battalions unable to do required maintenance or repairs.


title: Tiger I

text: On 11 April 1945, a Tiger I destroyed three M4 Sherman tanks and an armoured car advancing on a road. On 12 April 1945, a Tiger I (F02) destroyed two Comet tanks, one half-track and one scout car. This Tiger I was destroyed by a Comet tank of A Squadron of the 3rd Royal Tank Regiment on the next day without infantry support.


title: Tiger I

text: The tank's weight significantly limited its use of bridges. For this reason, the Tiger was built with water tight hatches and a snorkel device that allowed it to ford water obstacles four metres deep. The tank's weight also made driving through buildings risky, as the presence of a cellar could result in a sudden drop. Due to reliability problems with the Maybach HL 210 TRM P45, which was delivered within the first production batch of 250 Tigers, performance for its maximum power output at high gear ratio could not be fulfilled. Though the Maybach engines had a maximum of 3,000 rpm, crews were told in the "Tigerfibel" not to exceed 2,600 rpm. The engine limitation was alleviated only by the adoption of the Maybach HL 230. The turret could also be traversed manually, but this option was rarely used, except when the engine was turned off or sometimes for very small adjustments.


title: Tiger I

text: Early Tigers had a top speed of about over optimal terrain. This was not recommended for normal operation, and was discouraged in training. An engine governor was subsequently installed, capping the engine at 2,600 rpm and the Tiger's maximum speed to about . Tiger crews report that typical march speed off-road was 10 km/h (6 mph). However, medium tanks of the time, such as the Sherman or T-34, had on average a top speed of about . Thus, despite the Tiger being nearly twice as heavy, its speed was comparatively respectable. With the tank's very wide tracks, a design feature borrowed from the Soviet T-34, the Tiger had a lower ground pressure than many smaller tanks, such as the M4 Sherman.


title: Tiger I

text: The first production series Tiger Fgst Nr 250001 with Motor Nr 46052 was only run-in for 25 km by Henschel before being sent to Kummersdorf for testing. During a test drive on 28 May 1942, with only 52 km on the odometer, a blockage occurred in the steering gear. This Tiger quickly went through the original and two replacement engines (Motor Nr 46051 from July lst to 3rd, Motor Nr 46065 from 6 to 8 July) and was fitted with a fourth motor, Nr 46066, after 13 July. By 3 August 1942, this Tiger had covered a total of 1046 km; by 31 March 1943 a total of 5623 km; and by 31 July 1943 a total of 7736 km.These figures clearly demonstrate that once the Tiger had overcome its teething troubles, it could withstand a lot of purposefully administered abuse during test programmes.


title: Tiger I

text: The "13.(Tiger) Kompanie/Panzer-Regiment Großdeutschland" reported on their experience in employing the Tiger from 7 to 19 March 1943:


title: Tiger I

text: Tiger I tanks needed a high degree of support. It required two or sometimes three of the standard German Sd.Kfz. 9 "Famo" heavy recovery half-track tractors to tow it. Tiger crews often resorted to using another Tiger to tow the damaged vehicle, but this was not recommended as it often caused overheating and engine breakdown. The low-mounted sprocket limited the obstacle clearance height. The tracks also had a tendency to override the rear sprocket, resulting in immobilisation. If a track overrode and jammed, two Tigers were normally needed to tow the tank. The jammed track was also a big problem itself, since due to high tension, it was often impossible to split the track by removing the track pins. The track sometimes had to be blown apart with a small explosive charge.


title: Tiger I

text: The average reliability of the Tiger tank in the second half of 1943 was similar to that of the Panther, 36%, compared to the 48% of the Panzer IV and the 65% of the StuG III. From May 1944 to March 1945, the reliability of the Tiger tank was comparable to the Panzer IV. With an average of 70%, the Tiger's operational availability on the Western Front, was better than 62% of Panthers. On the Eastern Front, 65% of Tigers were operationally available, compared to the 71% of Panzer IVs and 65% of Panthers.


title: Tiger I

text: Tigers were usually employed in separate heavy tank battalions ("schwere Panzer-Abteilung") under army command. These battalions would be deployed to critical sectors, either for breakthrough operations or, more typically, counter-attacks. A few favoured divisions, such as the "Grossdeutschland", and the 1st SS "Leibstandarte" Adolf Hitler, 2nd SS "Das Reich", and 3rd SS "Totenkopf" Panzergrenadier Divisions at Kursk, had a Tiger company in their tank regiments. The "Grossdeutschland" Division had its Tiger company increased to a battalion as the III Panzer Battalion of the Panzer Regiment "Grossdeutschland". 3rd SS "Totenkopf" retained its Tiger I company through the entire war. 1st SS and 2nd SS had their Tiger companies taken away and incorporated into the 101st SS Tiger Battalion, which was part of 1st SS Panzer Corps.


title: Tiger I

text: The Tiger was originally designed to be an offensive breakthrough weapon, but by the time it went into action, the military situation had changed dramatically, and its main use was on the defensive, as a mobile anti-tank and infantry gun support weapon. Tactically, this also meant moving the Tiger units constantly to parry breakthroughs, causing excessive mechanical wear. As a result, Tiger battalions rarely entered combat at full strength.


title: Tiger I

text: Against the Soviet and Western Allied production numbers, even a 10:1 kill ratio was not sufficient. These numbers must be set against the opportunity cost of the expensive Tiger. Every Tiger cost as much to build as four "Sturmgeschütz III" assault guns. (70,016 € or 72,068 USD Minus inflation)


title: Tiger I

text: The British had observed the gradual increase in German AFV armour and firepower since 1940 and had anticipated the need for more powerful anti-tank guns. Work on the 76.2 mm calibre Ordnance QF 17 pounder had begun in late 1940 and in 1942 100 early-production guns were rushed to North Africa to help counter the new Tiger threat. The gun carriage had not yet been developed, and the guns were mounted on the carriages of 25-pounder gun-howitzers and were known by the code name "Pheasant".


title: Tiger I

text: Efforts were hastened to get cruiser tanks armed with 17-pounder guns into operation. The Cruiser Mk VIII Challenger (A30) was already at the prototype stage in 1942, but this tank had relatively weaker armor with a front hull thickness of 64 mm. In the end, it was produced and deployed in limited numbers (around 200 were ordered in 1943), though crews liked it for its high speed. The extemporised Sherman Firefly, armed with the 17-pounder, proved to be an excellent anti-tank weapon, but the gun lacked general purpose capability until later in the war. Fireflies were successfully used against Tigers; in one engagement, a single Firefly destroyed three Tigers in 12 minutes with five rounds. Sherman Fireflies were deployed one per troop of four 75mm armed standard Shermans. The Germans learned to target Fireflies, so the gun barrel of the Firefly was painted to look like a standard M3 75mm gun. This was partially effective. Over 2,000 Fireflies were built during the war. Five different 17-pounder-armed British designs saw combat during the war: the Challenger, the A34 Comet (using the related QF 77mm HV), the Sherman Firefly, the 17pdr SP Achilles (upgunned M10 GMC), and the 17pdr SP Archer self-propelled gun, while one more, the A41 Centurion, was about to enter service as the European war ended. In 1944 the British introduced an APDS round for the 17-pounder, which increased penetration performance considerably.


title: Tiger I

text: Initially, the Soviets responded to the Tiger I by restarting production of the 57 mm ZiS-2 anti-tank gun (production was stopped in 1941 in favour of cheaper and more versatile alternatives – e.g. the ZiS-3 – as the gun's performance was excessive for early German armour). The ZiS-2 had better armour penetration than the 76 mm F-34 tank gun used by most Red Army tanks, or the ZiS-3 76 mm divisional cannon, but was still inadequate against Tigers. A small number of T-34s were again fitted with a tank version of the ZiS-2, the ZiS-4, but it could not fire an adequate high-explosive round, making it an unsuitable tank gun.


title: Tiger I

text: Firing trials of the new 85 mm D-5T also had proved disappointing. Several captured German Tiger I tanks were shipped to Chelyabinsk, where they were subjected to 85 mm fire from various angles. The 85 mm gun could not reliably penetrate the Tiger I's armour except at ranges within the lethal envelope of the Tiger I's own 88 mm gun. It was still initially used on the SU-85 self-propelled gun (based on a T-34 chassis) from August 1943. The production of KV heavy tanks armed with the 85 mm D-5T in an IS-85 turret was also started. There was a short production run of 148 KV-85 tanks, which were sent to the front beginning in September 1943 with production ending by December 1943. By early 1944, the T-34/85 appeared; this up-gunned T-34 matched the SU-85's firepower, but with the advantage of mounting the gun in a turret. It also matched the firepower of the heavier IS-85 tank in a more cost effective package resulting in a repetition of the events which heralded the decline of KV-1 production. The IS was subsequently rearmed with the 122 mm D-25T, which with BR–471 AP rounds was capable of going through the Tiger's armour from 1,200 m, and with the improved BR–471B APHEBC rounds at over 2,000 m. The redundant SU-85 was replaced by the SU-100, mounting a 100 mm D-10 tank gun, that could penetrate 149 mm of vertical armour plate at 1,000 m.


title: Tiger I

text: In May 1943, the Red Army deployed the SU-152, which was replaced in 1944 by the ISU-152. These self-propelled guns both mounted the large, 152 mm howitzer-gun. The SU-152 was intended to be a close-support gun for use against German fortifications rather than armour; however, it shared among the later fielded ISU-152, the nickname "Zveroboy" ("beast killer"), for its rare ability to knock out German heavy tanks. The 152 mm armour-piercing shells weighed over and could penetrate a Tiger's frontal armour from about . Its high-explosive rounds would destroy anything that was attached to the outside of the tank, and had a knack for immobilizing any tank it hit. The sheer force of the shell meant that at certain points it could knock off the turrets of the Tiger series. However, the size and weight of the ammunition meant both vehicles had a low rate of fire.


title: Tiger I

text: The US Army hesitated to place 76 mm M1 guns in action even when they were already available, as combat through early 1944 indicated that the 75 mm M3 was more than adequate for handling the German tank threat. This conclusion was partly based on the correct estimate that Tigers would be encountered in relatively small numbers, and on the assumption that anti-tank gun-fire (as in Tunisia and Sicily) rather than tanks could knock them out. But as early as 1942, the US was already planning and testing the rearming of the M4 Sherman with the 76mm gun, expecting to encounter heavier German armor later in the war.


title: Tiger I

text: On 21 April 1943, a Tiger I of the 504th German heavy tank battalion, with turret number 131, was captured on a hill called Djebel Djaffa in Tunisia. A 6-pounder solid shot from a Churchill tank of the British 48th Royal Tank Regiment hit the Tiger's gun barrel and ricocheted into its turret ring, jamming its traverse and wounding the commander. The crew bailed out and the tank was captured. After repairs, the tank was sent to England for a thorough inspection.


title: Tiger I

text: The captured tank was officially handed over to the Bovington Tank Museum by the British Ministry of Supply on 25 September 1951. In June 1990, the tank was removed from display at the museum and work began on its restoration. This was carried out both by the museum and the Army Base Repair Organisation and involved an almost complete disassembly of the tank. The Maybach HL230 engine from the museum's Tiger II was installed (the Tiger's original Maybach HL210 had been sectioned for display), along with a modern fire-suppressant system in the engine compartment. In December 2003, Tiger 131 returned to the museum, restored and in running condition. This Tiger was used in the film "Fury", the first time an original, fully mechanically operable Tiger I has appeared in a movie since World War II. The fire suppression system was removed as it interfered with engine maintenance and was too obtrusive.


title: Tiger I

text: Given the low number of just over 1,300 Tiger Is produced during World War II, very few survived the war and the subsequent post-war scrapping drives. Many large components have been salvaged over the years, but the discovery of a more or less and generally complete vehicle has so far eluded armour enthusiasts and tank collectors. In addition to Tiger 131, eight other Tiger I tanks survive:


title: Regression analysis

text: In statistical modeling, regression analysis is a set of statistical processes for estimating the relationships between a dependent variable (often called the 'outcome' or 'response' variable, or a 'label' in machine learning parlance) and one or more independent variables (often called 'predictors', 'covariates', 'explanatory variables' or 'features'). The most common form of regression analysis is linear regression, in which one finds the line (or a more complex linear combination) that most closely fits the data according to a specific mathematical criterion. For example, the method of ordinary least squares computes the unique line (or hyperplane) that minimizes the sum of squared differences between the true data and that line (or hyperplane). For specific mathematical reasons (see linear regression), this allows the researcher to estimate the conditional expectation (or population average value) of the dependent variable when the independent variables take on a given set of values. Less common forms of regression use slightly different procedures to estimate alternative location parameters (e.g., quantile regression or Necessary Condition Analysis) or estimate the conditional expectation across a broader collection of non-linear models (e.g., nonparametric regression).


title: Regression analysis

text: First, regression analysis is widely used for prediction and forecasting, where its use has substantial overlap with the field of machine learning.


title: Regression analysis

text: Second, in some situations regression analysis can be used to infer causal relationships between the independent and dependent variables. Importantly, regressions by themselves only reveal relationships between a dependent variable and a collection of independent variables in a fixed dataset. To use regressions for prediction or to infer causal relationships, respectively, a researcher must carefully justify why existing relationships have predictive power for a new context or why a relationship between two variables has a causal interpretation. The latter is especially important when researchers hope to estimate causal relationships using observational data.


title: Regression analysis

text: The earliest form of regression was the method of least squares, which was published by Legendre in 1805, and by Gauss in 1809. Legendre and Gauss both applied the method to the problem of determining, from astronomical observations, the orbits of bodies about the Sun (mostly comets, but also later the then newly discovered minor planets). Gauss published a further development of the theory of least squares in 1821, including a version of the Gauss–Markov theorem.


title: Regression analysis

text: The term "regression" was coined by Francis Galton in the 19th century to describe a biological phenomenon. The phenomenon was that the heights of descendants of tall ancestors tend to regress down towards a normal average (a phenomenon also known as regression toward the mean).


title: Regression analysis

text: For Galton, regression had only this biological meaning, but his work was later extended by Udny Yule and Karl Pearson to a more general statistical context. In the work of Yule and Pearson, the joint distribution of the response and explanatory variables is assumed to be Gaussian. This assumption was weakened by R.A. Fisher in his works of 1922 and 1925. Fisher assumed that the conditional distribution of the response variable is Gaussian, but the joint distribution need not be. In this respect, Fisher's assumption is closer to Gauss's formulation of 1821.


title: Regression analysis

text: In the 1950s and 1960s, economists used electromechanical desk "calculators" to calculate regressions. Before 1970, it sometimes took up to 24 hours to receive the result from one regression.


title: Regression analysis

text: Regression methods continue to be an area of active research. In recent decades, new methods have been developed for robust regression, regression involving correlated responses such as time series and growth curves, regression in which the predictor (independent variable) or response variables are curves, images, graphs, or other complex data objects, regression methods accommodating various types of missing data, nonparametric regression, Bayesian methods for regression, regression in which the predictor variables are measured with error, regression with more predictor variables than observations, and causal inference with regression.


title: Regression analysis

text: In practice, researchers first select a model they would like to estimate and then use their chosen method (e.g., ordinary least squares) to estimate the parameters of that model. Regression models involve the following components:


title: Regression analysis

text: In various fields of application, different terminologies are used in place of dependent and independent variables.


title: Regression analysis

text: Most regression models propose that formula_4 is a function of formula_2 and formula_8, with formula_5 representing an additive error term that may stand in for un-modeled determinants of formula_4 or random statistical noise:


title: Regression analysis

text: The researchers' goal is to estimate the function formula_12 that most closely fits the data. To carry out regression analysis, the form of the function formula_13 must be specified. Sometimes the form of this function is based on knowledge about the relationship between formula_4 and formula_2 that does not rely on the data. If no such knowledge is available, a flexible or convenient form for formula_13 is chosen. For example, a simple univariate regression may propose formula_17, suggesting that the researcher believes formula_18 to be a reasonable approximation for the statistical process generating the data.


title: Regression analysis

text: Once researchers determine their preferred statistical model, different forms of regression analysis provide tools to estimate the parameters formula_19. For example, least squares (including its most common variant, ordinary least squares) finds the value of formula_19 that minimizes the sum of squared errors formula_21. A given regression method will ultimately provide an estimate of formula_1, usually denoted formula_23 to distinguish the estimate from the true (unknown) parameter value that generated the data. Using this estimate, the researcher can then use the "fitted value" formula_24 for prediction or to assess the accuracy of the model in explaining the data. Whether the researcher is intrinsically interested in the estimate formula_23 or the predicted value formula_26 will depend on context and their goals. As described in ordinary least squares, least squares is widely used because the estimated function formula_27 approximates the conditional expectation formula_28. However, alternative variants (e.g., least absolute deviations or quantile regression) are useful when researchers want to model other functions formula_29.


title: Regression analysis

text: It is important to note that there must be sufficient data to estimate a regression model. For example, suppose that a researcher has access to formula_30 rows of data with one dependent and two independent variables: formula_31. Suppose further that the researcher wants to estimate a bivariate linear model via least squares: formula_32. If the researcher only has access to formula_33 data points, then they could find infinitely many combinations formula_34 that explain the data equally well: any combination can be chosen that satisfies formula_35, all of which lead to formula_36 and are therefore valid solutions that minimize the sum of squared residuals. To understand why there are infinitely many options, note that the system of formula_33 equations is to be solved for 3 unknowns, which makes the system underdetermined. Alternatively, one can visualize infinitely many 3-dimensional planes that go through formula_33 fixed points.


title: Regression analysis

text: More generally, to estimate a least squares model with formula_39 distinct parameters, one must have formula_40 distinct data points. If formula_41, then there does not generally exist a set of parameters that will perfectly fit the data. The quantity formula_42 appears often in regression analysis, and is referred to as the degrees of freedom in the model. Moreover, to estimate a least squares model, the independent variables formula_43 must be linearly independent: one must "not" be able to reconstruct any of the independent variables by adding and multiplying the remaining independent variables. As discussed in ordinary least squares, this condition ensures that formula_44 is an invertible matrix and therefore that a unique solution formula_23 exists.


title: Regression analysis

text: By itself, a regression is simply a calculation using the data. In order to interpret the output of regression as a meaningful statistical quantity that measures real-world relationships, researchers often rely on a number of classical assumptions. These assumptions often include:


title: Regression analysis

text: A handful of conditions are sufficient for the least-squares estimator to possess desirable properties: in particular, the Gauss–Markov assumptions imply that the parameter estimates will be unbiased, consistent, and efficient in the class of linear unbiased estimators. Practitioners have developed a variety of methods to maintain some or all of these desirable properties in real-world settings, because these classical assumptions are unlikely to hold exactly. For example, modeling errors-in-variables can lead to reasonable estimates independent variables are measured with errors. Heteroscedasticity-consistent standard errors allow the variance of formula_5 to change across values of formula_2. Correlated errors that exist within subsets of the data or follow specific patterns can be handled using "clustered standard errors, geographic weighted regression", or Newey–West standard errors, among other techniques. When rows of data correspond to locations in space, the choice of how to model formula_5 within geographic units can have important consequences. The subfield of econometrics is largely focused on developing techniques that allow researchers to make reasonable real-world conclusions in real-world settings, where classical assumptions do not hold exactly.


title: Regression analysis

text: In linear regression, the model specification is that the dependent variable, formula_52 is a linear combination of the "parameters" (but need not be linear in the "independent variables"). For example, in simple linear regression for modeling formula_53 data points there is one independent variable: formula_54, and two parameters, formula_55 and formula_56:


title: Regression analysis

text: In multiple linear regression, there are several independent variables or functions of independent variables.


title: Regression analysis

text: This is still linear regression; although the expression on the right hand side is quadratic in the independent variable formula_60, it is linear in the parameters formula_55, formula_56 and formula_63


title: Regression analysis

text: In both cases, formula_64 is an error term and the subscript formula_3 indexes a particular observation.


title: Regression analysis

text: Returning our attention to the straight line case: Given a random sample from the population, we estimate the population parameters and obtain the sample linear regression model:


title: Regression analysis

text: The residual, formula_67, is the difference between the value of the dependent variable predicted by the model, formula_68, and the true value of the dependent variable, formula_69. One method of estimation is ordinary least squares. This method obtains parameter estimates that minimize the sum of squared residuals, SSR:


title: Regression analysis

text: Minimization of this function results in a set of normal equations, a set of simultaneous linear equations in the parameters, which are solved to yield the parameter estimators, formula_71.


title: Regression analysis

text: where formula_74 is the mean (average) of the formula_75 values and formula_76 is the mean of the formula_77 values.


title: Regression analysis

text: Under the assumption that the population error term has a constant variance, the estimate of that variance is given by:


title: Regression analysis

text: This is called the mean square error (MSE) of the regression. The denominator is the sample size reduced by the number of model parameters estimated from the same data, formula_79 for formula_80 regressors or formula_81 if an intercept is used. In this case, formula_82 so the denominator is formula_83.


title: Regression analysis

text: Under the further assumption that the population error term is normally distributed, the researcher can use these estimated standard errors to create confidence intervals and conduct hypothesis tests about the population parameters.


title: Regression analysis

text: If the first independent variable takes the value 1 for all formula_3, formula_92, then formula_56 is called the regression intercept.


title: Regression analysis

text: The least squares parameter estimates are obtained from formula_80 normal equations. The residual can be written as


title: Regression analysis

text: where the formula_98 element of formula_99 is formula_88, the formula_3 element of the column vector formula_102 is formula_69, and the formula_90 element of formula_105 is formula_106. Thus formula_99 is formula_108, formula_102 is formula_110, and formula_105 is formula_112. The solution is


title: Regression analysis

text: Once a regression model has been constructed, it may be important to confirm the goodness of fit of the model and the statistical significance of the estimated parameters. Commonly used checks of goodness of fit include the R-squared, analyses of the pattern of residuals and hypothesis testing. Statistical significance can be checked by an F-test of the overall fit, followed by t-tests of individual parameters.


title: Regression analysis

text: Interpretations of these diagnostic tests rest heavily on the model's assumptions. Although examination of the residuals can be used to invalidate a model, the results of a t-test or F-test are sometimes more difficult to interpret if the model's assumptions are violated. For example, if the error term does not have a normal distribution, in small samples the estimated parameters will not follow normal distributions and complicate inference. With relatively large samples, however, a central limit theorem can be invoked such that hypothesis testing may proceed using asymptotic approximations.


title: Regression analysis

text: Limited dependent variables, which are response variables that are categorical variables or are variables constrained to fall only in a certain range, often arise in econometrics.


title: Regression analysis

text: The response variable may be non-continuous ("limited" to lie on some subset of the real line). For binary (zero or one) variables, if analysis proceeds with least-squares linear regression, the model is called the linear probability model. Nonlinear models for binary dependent variables include the probit and logit model. The multivariate probit model is a standard method of estimating a joint relationship between several binary dependent variables and some independent variables. For categorical variables with more than two values there is the multinomial logit. For ordinal variables with more than two values, there are the ordered logit and ordered probit models. Censored regression models may be used when the dependent variable is only sometimes observed, and Heckman correction type models may be used when the sample is not randomly selected from the population of interest. An alternative to such procedures is linear regression based on polychoric correlation (or polyserial correlations) between the categorical variables. Such procedures differ in the assumptions made about the distribution of the variables in the population. If the variable is positive with low values and represents the repetition of the occurrence of an event, then count models like the Poisson regression or the negative binomial model may be used.


title: Regression analysis

text: When the model function is not linear in the parameters, the sum of squares must be minimized by an iterative procedure. This introduces many complications which are summarized in Differences between linear and non-linear least squares.


title: Regression analysis

text: Regression models predict a value of the "Y" variable given known values of the "X" variables. Prediction "within" the range of values in the dataset used for model-fitting is known informally as interpolation. Prediction "outside" this range of the data is known as extrapolation. Performing extrapolation relies strongly on the regression assumptions. The further the extrapolation goes outside the data, the more room there is for the model to fail due to differences between the assumptions and the sample data or the true values.


title: Regression analysis

text: It is generally advised that when performing extrapolation, one should accompany the estimated value of the dependent variable with a prediction interval that represents the uncertainty. Such intervals tend to expand rapidly as the values of the independent variable(s) moved outside the range covered by the observed data.


title: Regression analysis

text: However, this does not cover the full set of modeling errors that may be made: in particular, the assumption of a particular form for the relation between "Y" and "X". A properly conducted regression analysis will include an assessment of how well the assumed form is matched by the observed data, but it can only do so within the range of values of the independent variables actually available. This means that any extrapolation is particularly reliant on the assumptions being made about the structural form of the regression relationship. Best-practice advice here is that a linear-in-variables and linear-in-parameters relationship should not be chosen simply for computational convenience, but that all available knowledge should be deployed in constructing a regression model. If this knowledge includes the fact that the dependent variable cannot go outside a certain range of values, this can be made use of in selecting the model – even if the observed dataset has no values particularly near such bounds. The implications of this step of choosing an appropriate functional form for the regression can be great when extrapolation is considered. At a minimum, it can ensure that any extrapolation arising from a fitted model is "realistic" (or in accord with what is known).


title: Regression analysis

text: There are no generally agreed methods for relating the number of observations versus the number of independent variables in the model. One method conjectured by Good and Hardin is formula_114, where formula_30 is the sample size, formula_116 is the number of independent variables and formula_117 is the number of observations needed to reach the desired precision if the model had only one independent variable. For example, a researcher is building a linear regression model using a dataset that contains 1000 patients (formula_30). If the researcher decides that five observations are needed to precisely define a straight line (formula_117), then the maximum number of independent variables the model can support is 4, because


title: Regression analysis

text: Although the parameters of a regression model are usually estimated using the method of least squares, other methods which have been used include:


title: Regression analysis

text: All major statistical software packages perform least squares regression analysis and inference. Simple linear regression and multiple regression using least squares can be done in some spreadsheet applications and on some calculators. While many statistical software packages can perform various types of nonparametric and robust regression, these methods are less standardized. Different software packages implement different methods, and a method with a given name may be implemented differently in different packages. Specialized regression software has been developed for use in fields such as survey analysis and neuroimaging.


title: Indian Administrative Service

text: The Indian Administrative Service (IAS) is the administrative arm of the All India Services of Government of India. Considered the premier civil service of India, the IAS is one of the three arms of the All India Services along with the Indian Police Service and the Indian Forest Service. Members of these three services serve the Government of India as well as the individual states. IAS officers are also deployed to various government establishments such as constitutional bodies, staff & line agencies, auxiliary bodies, public sector units, regulatory bodies, statutory bodies and autonomous bodies.


title: Indian Administrative Service

text: As with other countries following the parliamentary system of government, the IAS is a part of the permanent bureaucracy of the nation, and is an inseparable part of the executive of the Government of India. As such, the bureaucracy remains politically neutral and guarantees administrative continuity to the ruling party or coalition.


title: Indian Administrative Service

text: Upon confirmation of service, an IAS officer serves a probationary period as a sub-divisional magistrate. Completion of this probation is followed by an executive administrative role in a district as a district magistrate and collector which lasts several years. After this tenure, an officer may be promoted to head a whole state administrative division, as a divisional commissioner.


title: Indian Administrative Service

text: On attaining the higher scales of the pay matrix, IAS officers may lead government departments or ministries. In these roles, IAS officers represent the country at the international level in bilateral and multilateral negotiations. If serving on a deputation, they may be employed in intergovernmental organisations such as the World Bank, the International Monetary Fund, the Asian Development Bank, the Asian Infrastructure Investment Bank, or the United Nations, or its agencies. IAS officers are also involved in the conduct of elections in India as mandated by the Election Commission of India.


title: Indian Administrative Service

text: During the East India Company period, the civil services were classified into threecovenanted, uncovenanted and special civil services. The covenanted civil service, or the Honourable East India Company's Civil Service (HEICCS), as it was called, largely comprised civil servants occupying the senior posts in the government. The uncovenanted civil service was introduced solely to facilitate the entry of Indians onto the lower rung of the administration. The special service comprised specialised departments, such as the Indian Forest Service, the Imperial Police and the Indian Political Service, whose ranks were drawn from either the covenanted civil service or the Indian Army. The Imperial Police included many Indian Army officers among its members, although after 1893 an annual exam was used to select its officers. In 1858 the HEICCS was replaced by the Indian Civil Service (ICS), which became the highest civil service in India between 1858 and 1947. The last appointments to the ICS were made in 1942.


title: Indian Administrative Service

text: With the passing of the Government of India Act 1919 by the Parliament of the United Kingdom, the Indian civil services—under the general oversight of the Secretary of State for India—were split into two arms, the All India Services and the Central Services. The Indian Civil Service was one of the ten All India Services.


title: Indian Administrative Service

text: In 1946 at the Premier's Conference, the Central Cabinet decided to form the Indian Administrative Service, based on the Indian Civil Service; and the Indian Police Service, based on the Imperial Police.


title: Indian Administrative Service

text: When India was partitioned following the departure of the British in 1947, the Indian Civil Service was divided between the new dominions of India and Pakistan. The Indian remnant of the ICS was named the Indian Administrative Service, while the Pakistani remnant was named the Pakistan Administrative Service. The modern Indian Administrative Service was created under Article 312(2) in part XIV of the Constitution of India, and the All India Services Act, 1951.


title: Indian Administrative Service

text: A special cadre was created in 1954 to administer NEFA (present day Arunachal Pradesh) and for later all North Eastern Region. It was first mooted by then Prime Minister Jawahar Lal Nehru.


title: Indian Administrative Service

text: In 1968, IFAS was merged with IAS. However Chief Ministers from Arunachal Pradesh and Mizoram revival of IFAS.


title: Indian Administrative Service

text: There are three modes of recruitment into the Indian Administrative Service. IAS officers may enter the IAS by passing the Civil Services Examination, which is conducted by the Union Public Service Commission (UPSC). Officers recruited this way are called direct recruits. Some IAS officers are also recruited from the state civil services, and, in rare cases, selected from non-state civil service. The ratio between direct recruits and promotees is fixed at 2:1. All IAS officers, regardless of the mode of entry, are appointed by the President of India.


title: Indian Administrative Service

text: Only about 180 candidates out of over 1million applicants, who apply through CSE, are successful, a success rate of less than 0.02percent.


title: Indian Administrative Service

text: Unlike candidates appointed to other civil services, a successful IAS candidate is rendered ineligible to retake CSE. From 1951 to 1978, an IAS candidate was required to submit two additional papers, as well as three optional papers (instead of two as with other civil services) to be eligible for the Indian Administrative Service or the Indian Foreign Service. The two additional papers were postgraduate level submissions, compared to the graduate level of the optional papers, and it was this distinction that resulted in a higher status for the IAS and IFS. The two postgraduate level submissions were later removed, but this has not changed the perceived higher status of the IAS and IFS. After the selection process, the successful candidates undergo training at the Lal Bahadur Shastri National Academy of Administration in Mussoorie, Uttarakhand.


title: Indian Administrative Service

text: The central government announced a new cadre allocation policy for the All India Services in August 2017, touting it as a policy to ensure national integration of the bureaucracy and to ensure an All India character of the services. The existing twenty O sixcadres were to be divided into fivezones by the Department of Personnel and Training. Under the new policy, a candidate first selects their zones of preference, in descending order, then indicates a cadre preference from each preferred zone. The candidate indicates their second cadre preference for every preferred zone subsequently. The preference for the zones and cadres remains in the same order and no change is permitted.


title: Indian Administrative Service

text: Until 2008, there was no formal system that permitted the selection of a state cadre preferred by the candidate. If the candidate was not placed in a vacancy in their home state, they would be allocated to other states, which were selected from a roster in alphabetic order, starting from 'a', 'h', 'm' or 't', depending on the year. For example, if in a particular year the roster begins from 'a', then the first candidate on the roster will go to the Andhra Pradesh state cadre, the next one to Bihar, and then to Chhattisgarh, Gujarat and so on in alphabetical order. The next year the roster starts from 'h', for either Haryana or Himachal Pradesh (the two states alternate roster years). This system, practised since the mid-1980s, ensured that officers from different states were placed all over India.


title: Indian Administrative Service

text: The system of permanent state cadres resulted in wide disparities of professional exposure for officers when comparing those from developed versus less developed states. Changes in state cadres were only permitted on grounds of marriage to an All India Services officer of another state cadre or under other exceptional circumstances. The officers were allowed to go to their home state cadre on deputation for a limited period after which they would be required to return to their allocated cadre.


title: Indian Administrative Service

text: From 2008, IAS officers were assigned to state cadres at the beginning of their service. There was one cadre for each Indian state, except for twojoint cadres: Assam–Meghalaya and Arunachal Pradesh–Goa–Mizoram–Union Territories (AGMUT). The "insider-outsider ratio" (ratio of officers who were posted to their home states to those from other states) was maintained at 1:2, with one-third of the direct recruits being 'insiders' from the same state. The rest were posted as outsiders according to the state allocation roster in states other than their home states, as indicated by their preference.


title: Indian Administrative Service

text: At the beginning of their career, IAS officers receive district training with their home cadres followed by their first posting. Their initial role is as a assistant collector cum sub-district magistrate and they are placed in charge of a district sub-division. As assistant collector cum sub district magistrate, they are entrusted with maintaining law and order, as well as general administration and development work, of the sub-district. With the completion of their training, IAS officers are assigned to various designations in various "ministries", "departments" and "establishments" under the ownership of the union government, state governments and in local governments (municipal corporations,


title: Indian Administrative Service

text: notified area councils and municipal councils at urban level and gram panchayats, prakhand parishads and zilla parishads at rural level).


title: Indian Administrative Service

text: In 2015 it was announced that a new designation of assistant secretary at the Central Secretariat had been created to enable new IAS officers to be posted to Delhi for a three-month assignment as part of their training regime. IAS officers were previously only permitted to go on a deputation once assigned to the Central Secretariat after nine years of service in their home cadre. It was observed that the experience of central functions was severely lacking among these deputations, resulting in this change in their training. As part of the new system, IAS assistant secretaries are supposed to work on projects—a new policy in their respective areas—and present it to their respective ministries; of all projects, 36 are selected to be presented before all secretaries of the Government of India; consequently, 16 are selected to be before the Cabinet Secretary and a final eight are selected for presentation before the Prime Minister.


title: Indian Administrative Service

text: Completion of this probation is followed by an executive role in a district as a collector cum district magistrate, which lasts several years. After this tenure as a district magistrate, the officer may be promoted to head a whole state division, as a divisional commissioner.


title: Indian Administrative Service

text: On attaining the apex scale, IAS officers may lead government departments or ministries. In these roles, IAS officers represent the country at the international level in bilateral and multilateral negotiations. If serving on a deputation, they may be employed in intergovernmental organisations such as the World Bank, the International Monetary Fund, the Asian Development Bank, the Asian Infrastructure Investment Bank, and the United Nations or its agencies. IAS officers are also involved in the conduct of elections in India as mandated by the Election Commission of India.


title: Indian Administrative Service

text: Upon retirement, high ranking IAS officers have occupied constitutional posts such as the Chief Election Commissioner of India, the Comptroller and Auditor General of India, and the chairperson of the Union Public Service Commission (UPSC). They have also become members of administrative tribunals, such as the National Green Tribunal and the Central Administrative Tribunal, as well as chiefs of regulators including the Telecom Regulatory Authority of India, the Securities and Exchange Board of India, and the Reserve Bank of India. If a serving IAS officer is appointed to a constitutional post such as Comptroller and Auditor General of India, Chief Election Commissioner of India or chairperson of UPSC or as head of a statutory authority, such as the National Commission for Women or the Central Information Commission, he or she is deemed to have retired from service.


title: Indian Administrative Service

text: IAS officers can also be deputed to private organisations for a fixed tenure under Rule 6(2)(ii) of the Indian Administrative Service (Cadre) Rules, 1954.


title: Indian Administrative Service

text: The performance of IAS officers is assessed through a performance appraisal report. The reports are reviewed to judge the suitability of an officer before a promotion or a posting in the union or state governments. The report is compiled annually and is initiated by the officers themselves, designated as the reporting officer, who list their achievements, completion of assigned activities and targets for the year. The report is then modified and commented on by the reviewing officer, usually the superior of the reporting officer. All the Reports are forwarded by the reviewing officer to the accepting authority, who conducts a final review of the report.


title: Indian Administrative Service

text: It was reported in 2017 that there is a shortage of about 1,700IAS officers in the country. Despite this, the government has stated that annual recruitment of IAS officers will not increase, to avoid impacting the career progression of existing officers and the overall structure of the service.


title: Indian Administrative Service

text: Media personalities, some retired IAS officers and a few academics have argued in favour of lateral entry into the IAS to inject fresh blood into the service. They argue that it would help refresh the bureaucracy, offer competitiveness and bring in alternate perspectives. A counter-argument has been put forward that a lateral entry process could be manipulated due to corruption and cronyism. It is further argued that lateral entry would not lead to improvements in managerial performance or accountability, and while it may create synergy between the government and big businesses, it could also compromise the integrity of government. It has also been argued that it could weaken the bureaucracy instead. The union government has frequently ruled out lateral entry into the IAS.


title: Indian Administrative Service

text: Several think tanks and media outlets have argued that the IAS is hamstrung by political influence within the service. It has been reported that many local political leaders have been seen to have interfered with IAS officers. Politicians have also exerted pressure on IAS officers by repeatedly transferring them, suspending them, beating them, and, in some extreme cases, killing them.


title: Indian Administrative Service

text: While hearing "T. S. R. Subramanian v. Union of India", the Supreme Court of India ruled that IAS officersand other civil servantswere not required to act on oral instructions given by politicians as they 'undermined credibility'.


title: Indian Administrative Service

text: Several academic papers have shown IAS to be a significant contributor to crony capitalism in India. In 2015, it was reported by the Government of India that a hundred IAS officers had come under scrutiny by the Central Bureau of Investigation for alleged corruption. In 2017 Government records showed that 379 IAS officers had deliberately failed to submit details of their immovable assets (IPR). Since 2007, a number of chief secretaries and a principal secretary have been arrested in cases of graft or money laundering. IAS officers have been found amassing disproportionate assets and wealth varying from , to . In 2016 it was reported that the Government would provide the means to prosecute corrupt IAS officers, with the Ministry of Personnel, Public Grievances and Pensions agreeing to receive requests from private citizens seeking punitive measures against IAS officers even without supporting documentation.


title: Indian Administrative Service

text: In 2017, a Central Bureau of Investigation special court in Delhi sentenced a former Union Coal Secretary and two other IAS officers to two years in prison for their involvement in the coal allocation scam.


title: Indian Administrative Service

text: In 2017 it was reported by the Department of Personnel and Training, part of the Ministry of Personnel, Public Grievances and Pensions, that, since 2014, one IAS officer was prematurely retired from service, ten IAS officers had been deemed to have resigned, five had their pensions cut, and a further eight IAS officers suffered a cut in remuneration.


title: Indian Administrative Service

text: In 2018 the Union Minister of State for Personnel, Public Grievances and Pensions, Jitendra Singh, informed the Lok Sabha that disciplinary proceedings were underway against 36 IAS officers. In 2020, Central Bureau of Investigation arrested two district magistrates in connection with an illegal arms license distribution scandal in the then Jammu & Kashmir state.


title: Indian Administrative Service

text: During year 2020–21, 581 corruption charges were filed against IAS officers. Further, a total of 753 complaints were received against the IAS officers in 2019-20 and 643 in 2018–19.


title: Indian Administrative Service

text: In June 2015, "The Telegraph" reported that twelve IAS officers had gone missing, and had not reported to either the union or the state government for their allocated cadre. It was believed that they were working in foreign countries for companies such as Microsoft for more lucrative pay. "The Asian Age" later reported that the services of three of the twelve officers were likely to be terminated due to "prolonged absence from service".


title: Jason Derulo

text: Jason Joel Desrouleaux (born September 21, 1989), known professionally as Jason Derulo (; formerly stylized as Derülo), is an American singer and songwriter. Since the start of his solo recording career in 2009, he has sold over 30 million singles and has achieved eleven platinum singles including "Wiggle", "Talk Dirty", "Want to Want Me", "Trumpets", "It Girl", "In My Head", "Ridin' Solo", and "Whatcha Say".


title: Jason Derulo

text: After contributing and writing songs for various artists, Derulo signed to recording label Beluga Heights, owned by record producer and industry veteran J. R. Rotem. After Beluga Heights became part of the Warner Music Group, Derulo became a recording artist and released his debut single "Whatcha Say" in May 2009. It sold over five million digital downloads, gaining an RIAA certification of triple platinum, and reaching number one in the U.S. and New Zealand. Derulo released his second single, "In My Head", in December 2009 and his self-titled debut studio album "Jason Derulo", followed on March 2, 2010. He released his second album, "Future History", on September 16, 2011; the album was preceded by the release of the UK number-one single "Don't Wanna Go Home". Derulo's third international album, "Tattoos", was released on September 24, 2013, and later repackaged as his third U.S. album, "Talk Dirty", released on April 15, 2014. In 2015, Derulo released his single "Want to Want Me" and announced his fourth studio album, "Everything Is 4", which was released on June 2, 2015.


title: Jason Derulo

text: In June 2020, Derulo released the single "Savage Love (Laxed – Siren Beat)" alongside beat producer Jawsh 685. The song went viral on TikTok and was later remixed by BTS, wherein the remix reached number one in the US, becoming Derulo's second chart-topper in the region. In November 2020, Derulo released another single entitled "Love Not War (The Tampa Beat)" featuring New Caledonian beat producer Nuka. It was inspired from the latter's SoundCloud track known as "The Tampa Beat" which was earlier released in 2018, and has been used in over 23 million TikTok videos.


title: Jason Derulo

text: Derulo was born in Miramar, Florida, the son of Haitian parents. Derulo's first language was Creole and his mother went to law school. He started singing at a young age. He attended performing arts schools in Florida and made some early attempts at music composition, writing his first song at the age of eight. His writing skills began attracting attention when he was a teenager. He also wrote "Bossy" for Birdman, a New Orleans-based rapper, and made a guest appearance on the song, highlighting his ability as a vocalist.


title: Jason Derulo

text: Derulo has been writing songs for artists including Diddy, Danity Kane, Donnie Klang, Sean Kingston, Cassie, and Lil Wayne since he was young, also intending on becoming a solo performer. After attending performing arts schools, such as The American Musical and Dramatic Academy, and honing his talents as a singer and dancer, as well as acting in theatre productions like "Ragtime" and "Smokey Joe's Cafe", Derulo won the grand prize on the 2006 season finale of the TV show "Showtime at the Apollo". Derulo was discovered by music producer J.R. Rotem, who signed him to his record label Beluga Heights Records and Warner Bros. Records.


title: Jason Derulo

text: In a HitQuarters interview, Rotem highlighted Derulo's dedication to his art by saying, "Jason Derulo has one of the most impressive work ethics I've ever come across – he just keeps knocking out songs in the studio. That's an amazing quality."


title: Jason Derulo

text: On August 4, 2009, Jason released his debut single, "Whatcha Say". It was produced by J.R. Rotem with additional production by Fuego. The track heavily samples the Imogen Heap song "Hide and Seek". In late August 2009, the song debuted at number 54 on the "Billboard" Hot 100 and hit number 1 in November 2009. It was Derulo's first number-one hit. The single's music video was released in September 2009; after the single became successful, Derulo began work on his debut album. He released the second single from his album, "In My Head", on December 8, 2009. It debuted at number 63 on the "Billboard" Hot 100, and reached number five.


title: Jason Derulo

text: Derulo's debut album, "Jason Derulo", stylised with an umlaut as "Jason Derülo", was released on March 2, 2010. "Jason Derulo" first charted within the top ten of the UK and Irish Albums Charts in early March 2010. He spent six weeks promoting the album in his appearances as one of the opening acts for Lady Gaga's 2009–2010 The Monster Ball Tour. The third single of the album is "Ridin' Solo", which was released worldwide on April 26, 2010. By July, the single had reached number nine in the "Billboard" Hot 100. Derulo has also been featured in a song by new artist Will Roush called "Turn it Up", which also features Stat Quo and Young Buck. He also collaborated with UK singer Pixie Lott on a song titled "Coming Home" from the re-released edition of her album "Turn It Up".


title: Jason Derulo

text: In 2011, Derulo recorded a track with Demi Lovato titled "Together" for her album "Unbroken". His second studio album, "Future History", was released on September 27, 2011. Derulo detailed his journey recording the album via a series of webisodes posted on his official website. Its lead single, "Don't Wanna Go Home", was released on May 20, 2011. It landed the number-one spot in the UK and in the top five in Australia. Derulo planned to embark on an eight-date UK tour in support of the album in February 2012, including a show at Wembley Arena on March 1. However, on January 3, 2012, while Derulo was rehearsing for his Future History Tour, he broke one of his vertebrae. As a result, he canceled all of his tour dates.


title: Jason Derulo

text: On March 28, 2012, Derulo appeared on "American Idol" to announce he would allow fans to help him finish the lyrics for a new song entitled "Undefeated", as part of a partnership with "American Idol" and Coca-Cola. Fans were given the opportunity to submit their own lyrics to complete the song, and fans were then given the chance to vote on which lyrics they liked the most. After doing an endurance test of 50 backflips in a row, Derulo broke his C2 vertebrate, also known as the hangman's break. On May 5, 2012, Derulo announced that his first post-neck injury television performance would be on the eleventh-season finale of "American Idol", on May 22, 2012. In August 2012, Derulo became a dance master alongside Kelly Rowland, for the first season of the Australian dance talent show "Everybody Dance Now". The show was cancelled shortly after its fourth episode aired due to poor ratings.


title: Jason Derulo

text: On July 9, 2012, Derulo announced that he had signed Australian singer-songwriter Arlene Zelina to his record label Future History (co-owned with his manager Frank Harris) after he attended one of her performances at Whisky a Go Go in 2011 before she returned to Melbourne, Australia. On July 10, 2012, Derulo confirmed this on his Twitter.


title: Jason Derulo

text: On April 16, 2013, Derulo released his single, "The Other Side" to radio on April 23, 2013. As of July 4, 2013 "The Other Side" peaked at No. 18 on the "Billboard" Hot 100. Derulo announced via Twitter that his third album would be called "Tattoos". The album was released on September 24, 2013. The album's second single, "Talk Dirty", was released internationally on July 27, 2013 (digitally). "Talk Dirty" peaked at number three on the "Billboard" Hot 100.


title: Jason Derulo

text: The album features American hip-hop recording artist 2 Chainz; it is the first single from Derulo to contain a feature. The tracks accompanying music video had already been shot and was released in early August 2013.


title: Jason Derulo

text: "Marry Me" made its US radio premiere on "On Air with Ryan Seacrest" on August 26, 2013. It was scheduled to be released to all digital retailers as the second single to the U.S. market, third overall, on the same day. On December 11, 2013, he was the headline act for Radio City Live in the Echo Arena, Liverpool. He performed Ridin' Solo and Talk Dirty.


title: Jason Derulo

text: Six months after Derulo's third album "Tattoos" was released (other than in the U.S) he announced on March 18, 2014, that he would be releasing an album with 4 newly recorded songs and 7 from "Tattoos" as the U.S album and that it would have different artwork and be re-titled "Talk Dirty". "Talk Dirty" was released on April 15, 2014. That same day, Jason Derulo released the special edition of "Tattoos" in the UK, which included the 4 new songs from the "Talk Dirty" album.


title: Jason Derulo

text: On November 21, 2014, Pitbull released a song off the album "Globalization" featuring Jason Derulo and Juicy J titled "Drive You Crazy", which was later to become a single on August 21, 2015.


title: Jason Derulo

text: On January 22, 2015, Dick Clark Productions announced that Derulo would be a judge in the upcoming 12th season of "So You Think You Can Dance", alongside new judge Paula Abdul and returning judge Nigel Lythgoe. "I am truly excited, and eagerly look forward to joining the cast of "So You Think You Can Dance"," said Derulo. "It is one of the most respected and longest-tenured shows on network television, and I hope to be a part of new growth and continued success."


title: Jason Derulo

text: On March 9, Derulo released the first single from his forthcoming fourth studio album, "Everything Is 4", called "Want to Want Me". "Want To Want Me" became the most-added track in the history of Top 40 radio: it was added to 156 monitored pop stations, making it the biggest Top 40 US radio launch thus far. It peaked at number five on the "Billboard" Hot 100 and topped the UK Singles Chart. The music video for his second single, "Cheyenne", was released on June 30, 2015.


title: Jason Derulo

text: On June 29, Derulo announced the release of his first greatest hits album, titled "Platinum Hits". Platinum Hits was released on July 29, 2016, with a brand-new song called "Kiss the Sky", which appears on the soundtrack to the film "Storks". The album features 11 platinum certified singles.


title: Jason Derulo

text: On February 24, 2017, Derulo released a new single entitled "Swalla", featuring Nicki Minaj and Ty Dolla $ign. On March 17, Pitbull and Derulo released the song "Educate Ya", from the former's album "Climate Change". On March 31, Cheyenne Frontier Days announced they added Jason Derulo to their 2017 Frontier Nights concert lineup on Friday, July 28, 2017. At the 2017 Billboard Music Awards on May 21, Derulo announced that his next studio album would be titled "777". ""If I'm Lucky" was then released on September 1. "Tip Toe" (featuring French Montana) was released soon after, on November 10. "Swalla" and "Tip Toe" were expected to be included on the album, according to Derulo. The album was later renamed "2Sides". Derulo explains the reason why he changed the album's name, saying:


title: Jason Derulo

text: "Goodbye", a joint-collaboration with David Guetta and featuring Nicki Minaj and Willy William, was released on August 24, 2018. In 2019, Derulo released the singles "Let's Shut Up & Dance" with Lay Zhang and NCT 127 on February 22, "Mamacita", featuring Farruko, on July 5, and "Too Hot" on August 27.


title: Jason Derulo

text: In a telephone interview with the Official Charts Company, Derulo revealed that he will release "a seven-track EP and then another one shortly after", and that his previous singles "Swalla", "If I'm Lucky", "Tip Toe", and "Goodbye" will not be included on this project because "those songs have had their time. Even though putting them on an album would make it go platinum in two seconds, it’s not about the numbers. These are brand new songs, brand new vibes." "Side 1", the first part of "2Sides", was released on November 8, 2019; with Part 2 arriving in 2020. Derulo stars as Rum Tum Tugger in the film "Cats", which premiered on December 20, 2019. He will also star as Isley Brothers frontman Ron Isley in the upcoming biographical film "Spinning Gold".


title: Jason Derulo

text: In May 2020, Derulo confirmed that after a lengthy negotiation, he had left his record contract with Warner Bros. Records due to creative differences. By leaving the label, Derulo also cancelled the release of "2Sides (Side 2)", but confirmed that new music would arrive later in 2020.


title: Jason Derulo

text: In June 2020, "Savage Love (Laxed – Siren Beat)" by Derulo and Jawsh 685 went viral on TikTok, eventually peaking at number one in the UK, becoming Derulo's 5th number one in the country. The song was originally released without properly clearing and attributing a prominent sample in the song to Jawsh 685. The clearance issue was resolved and the song was eventually re-released and credited to both artists.


title: Jason Derulo

text: The song was later on remixed by BTS, wherein the remix reached number one on the "Billboard" Hot 100, becoming Derulo's second chart topper in the region (his first since "Whatcha Say" in 2009, the longest time in between number-one hits for male artists since Dr. Dre's "Crack a Bottle" reached number one after a 12-year hiatus in 2009).


title: Jason Derulo

text: Derulo's music is generally pop, but also incorporates R&B and hip-hop influences. He has predominantly named Michael Jackson as his inspiration. Derulo states "He is the reason I am who I am today. When I was 4 years old, I saw him for the first time. I saw how he moved the crowd and how people were just so touched". His other musical influences include Elvis Presley, Madonna, Prince, Usher and Justin Timberlake. "Billboard"s Jason Lipshutz speaks on his overall music and sound stating he operates "in two musical modes", describing one as "positive PG-romance dance-pop personality", and the other as a "bumping, faux-crass club thumpers". He explained that "Derulo has been tweaking his two modes just enough as they are used to offset each other, so that audiences never grew sick of either style".


title: Jason Derulo

text: Derulo and singer Jordin Sparks dated for three years, before ending their relationship in September 2014. On May 8, 2021, he had a son with his girlfriend Jena Frumes. The couple broke up on September 23, 2021.


title: Huntsman spider

text: Huntsman spiders, members of the family Sparassidae (formerly Heteropodidae), are known by this name because of their speed and mode of hunting. They are also called giant crab spiders because of their size and appearance. Larger species sometimes are referred to as wood spiders, because of their preference for woody places (forests, mine shafts, woodpiles, wooden shacks). In southern Africa the genus "Palystes" are known as rain spiders or lizard-eating spiders. Commonly, they are confused with baboon spiders from the Mygalomorphae infraorder, which are not closely related.


title: Huntsman spider

text: More than a thousand Sparassidae species occur in most warm temperate to tropical regions of the world, including much of Australasia, Africa, Asia, the Mediterranean Basin, and the Americas.


title: Huntsman spider

text: Several species of huntsman spider can use an unusual form of locomotion. The wheel spider ("Carparachne aureoflava") from the Namib uses a cartwheeling motion which gives it its name, while "Cebrennus rechenbergi" uses a handspring motion.


title: Huntsman spider

text: Sparassids are eight-eyed spiders. The eyes appear in two largely forward-facing rows of four on the anterior aspect of the prosoma. Many species grow very large – in Laos, male giant huntsman spiders ("Heteropoda maxima") attain a legspan of . Persons unfamiliar with spider taxonomy commonly confuse large species with tarantulas, but huntsman spiders can generally be identified by their legs, which, rather than being jointed vertically relative to the body, are twisted in such a way that in some attitudes the legs extend forward in a crab-like fashion.