For his history class, Deshaun has to write a research paper on the causes of World War II. He bases most of his argument on a single book. After reading the rough draft, his professor tells him that before he realized so much on this one book, he needs to look at other books and articles on the topic. As he does so, Deshaun realizes that most other historians actually disagree with the conclusions made by the author of the first book. He even finds some articles where other historians specifically point out the problems they see with the book he was using. In this situation, Deshaun is coming to understand the concept of scholarship as conversation. At first, he did not understand that the book he found was not the final word on the topic. But as he read the additional books and articles, he came to see that his book was part of an ongoing debate that historians have been having on the topic, and that it represented only one perspective. He was surprised to realize that historians do not always agree. Instead, for many topics, there is not one clear answer that everyone accepts. As he comes to understand the idea of the scholarly conversation, Deshaun realizes that he cannot determine the value of any particular information source until he understands the broader conversation that is taking place around that source.


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Welcome to episode number seven of Splitting Hairs, the free salon education.com podcast powered by our friends at Minerva Beauty. If you're looking to upgrade your salon furniture, go check them out, MinervaBeauty.com. I got Brian Hare with me. Yeah, you do. Carly. Christina. What's up? It's an audio show. Hi. Make sure you hit that subscribe button, like the show, comment, please. We did get some more comments last week. I actually wanted to read those button. I forgot to put them on there, but a couple of people. Somebody said, have you heard the Lady Gaga song, Hair? Yeah, it's tattooed on my arm. Wait, and I was like, oh, did you put out a new song? And then I, so I went and listened to it. And then I realized it came out in like, 2015. We saw her perform it in concert, Matt. I know, we all were there. Am I anywhere? Really? You're never in the moment. We talked about this last night. You're never in the moment. I know it. Are you the body double? I'm like, multiplicity that movie. Are you the real Megan? No, you're not. No, are you the real Kate Middleton? Yeah. We found her. Could be. Yeah, man, I want to be, I got to be better at that. Anyways. Yeah, it's literally tattooed on my arm. That's funny. Okay. I never knew that's what that was. What'd you think I'm as free as my hair meant?  You know what? I didn't really think about it too much. All right, fair. All right, so follow us on Apple Podcasts and Spotify. We got a great show today. Excited to just kind of have some open discussions. So make sure you get involved in the chat and in the comments. Really today, we want to start off with a fun game. And the game is going to be, if you get five tools to use in your day. So like let's say today, you can only take five things into the salon to do all your clients. What would those five things be? I made my list. Do you want it? Yeah, that's fine. Well, I would take my swivel scissors that I got from you. Okay. My long YS part comb, I don't remember the number, but I just prefer, I'm more comfortable with the long comb clips because I have tried over the course of my career and I am not a good hairdresser without clips. Okay.  And my air wrap. And I can knock out everybody in the look great. Okay, but what if they want color? Sucks, not today. I need five things. You know, I was thinking about the five things and I was like, so... So one of them's the color bar, like... Well, the color bar, yeah, no. But I was thinking like, if you had to simplify the five things into actually having color that you could get by for the day, because like I understand and I'm not a colorist, so this is why this is so easy for me. But I could just definitely have Balayaj Lightner. Okay. And just talk everyone into highlights for that day. Like orange highlights? Yeah, orange ones. Yeah, who needs to tell me? Actually, if they wanted brighter ones, I'd just leave it on longer. And then if they wanted... Balayaj Lightner? If they wanted some red tones, then I just wouldn't leave it on as long. Matt, I suggest I have a couple of videos on YouTube about how to get nice bright highlights with Balayaj. Oh, great. Yeah, I'll watch this. It's not always just leaving it on longer. But wait, there's hair tutorials on YouTube? Yeah, it's on. Apparently not. Okay. Do you want to give your list? Yeah. Okay. I would say an extra long, rat tail comb. Wait, how long? Like the ones that I have. Like they're like really long. Like I don't like the short ones. I can't. Oh, all right. I know what you mean. Yeah, I use long ones too, I guess. Yeah. Because the short ones just look weird to me. Yeah. And they don't fit the foil. Yeah, and they don't pick up the hair. Like it just takes too long. Just for scratching itches. Yes. A foiling board. Cause I... I noticed we have a foiling board now. That's mine. And I was like, she worked somewhere else. That's what happened. I tried using it. I look very silly. I tried using it once too, cause I had one that somebody gave me. And I actually didn't mind it, but no one got into it at all. Yeah, I don't, like I'm trying to get it. It's just one of those things that it's like, oh, I don't have a ton of time. What do you like about it? So I will say the one that I got, I don't like the curve. I, when I worked at the other place, it was just flat. So it was really easy to just fold the foils onto that and just kind of like, you could fold all of your foils onto it and then fold them like, and it just was quicker. So you put a bunch of foils at once. Yeah. And I also like that. I don't know. I just feel like I have more control with it. I can really get like into, like in. I do like the, the nice even plane for pressure. Like when you do it, it's like, yeah, I can get in there. Dig through that. Oh yeah. Yeah, that's, yeah. Yeah, I love that. Okay. All right. So foiling board. Foiling board, foiling comb, long one. I suggest, I was going to say, I suggest you throw foils in there. Foils. Otherwise. Um, some kind of like conditioning treatment and toners. Okay. Yeah. Cause you're just going to be foiling toner. Yeah. All right. So then let me take the conditioning treatment and add some liner. You know what I miss? Talking about foils. She'll just chew off the rest of it. Yeah, that's fine. That's where I'll come in. Cause I'm only cutting there. Yeah, you guys can be a team for once. There you go. Perfect. There you go. No, talking about foils. I miss the, that roll that we had that went with the cart that you could clip like how long you wanted the foil. That was so convenient. The Minerva cart. Yeah. We should get more of that again. The roll foil. We can. Everyone said they didn't use it. I did. That's why we don't have anymore. I have such a hard time with the box. I don't know. I think I'm just. The boxes suck. I waste so much foil with those boxes.   I know.  That makes you feel better. Yeah. I usually take a lot of foils out. So we officially don't like box foils. Yeah. I mean, we need them because they're usually a great size.   Yeah, I like the roll foil too. I throw two extra foils on the ground just pulling the one out that I need. And then I gotta always turn the box every single one. No, it's a waste. It gets stuck. It is a waste. My client's like, no, you can use the one on the floor. I was like, no. State board. You're like, I can't. I can't. It touches the floor. It's dead. I'm paying for this. I'm sorry. I'm sorry. Fair. Reduce for you to recycle. I'm teasing. Don't come at us. All right, so. They were just here the other day. Stateboard. I know. Well, a couple of weeks ago. Yeah. She's super cool. You didn't see them? No. You were the only thing we got to write up about.  He picked up the foil off the floor. Yeah, that's what it was. No, everything was fine. It's so funny. They walk in. I feel like they walk in here. I didn't see them. You guys saw them, but they walk in here and I feel like they're just like, they don't really say much, right? I mean, or did they? No, she was cool. She was like. Yeah, they seem cooler than back in the day. See you in a couple of years. And that was like, okay, but you were just here. They were here. Yeah. It was odd. They always say that. And then I think they don't keep their job and then somebody else takes over and then they come back. And then it's always somebody different. All right. And then I guess my five tools, I would, for me, it's, I guess, a little bit easier because I would just pick haircutting stuff. But I was, I like a precision scissor texturizing a small comb, like the 339 or the 701, like that small comb.  So that's pretty much easy for me and not a round brush. I would, like a vent brush. Okay. I get so impatient. I'm, I try to get into a vent brush and I start so many blowouts with it. And like two minutes in, like, forget it. I'll just use my hand. Are you like a scraper? Like, like you are constantly brushing because I don't really brush a lot. I let the air kind of go over the hair and I kind of just, I'm letting the air do most of the work and like the brush. Yeah, Matt's not trying to come home sore. Well, I do a lot more long hair than Matt does too. Like I'm like using it to hold back or direction and all that. I'm like, my hand can do better. He does do a lot more hair in the salon. Like you're a lot more. Yeah. Which means like lengthwise. But lengthwise. Oh yeah, but like a lot more too. Yeah.  His girls. Who don't mind getting burned by a vent brush? They don't. They don't. She's like round brush, please. Did anybody have any ones in the chat that they would bring? No. I should stop saying that because no one even talks in there. No, people are saying, hey, like hello. All right, that's good. Hi, sir. Okay. Sir. Well, we have all different country. You know what I mean? So like the... Yeah. Don't get Matt addicted to sir. Yeah, don't be expecting it. Sir. Yes. Yes, sir. How'd this turn on me? I never asked you guys. Because I saw that twinkle in your eye when she read that comment. That's twinkle. Twinkle. A lot of people comment, sir. Yes, sir. All right. So I'm interested. Do you have five? Like I know you don't work in Islam, but like is there five things that you would be like, I would take? I would take one of my favorite stylists. And... She'd bring five, five of her favorite stylists. Just unleash them. A load of cash. Probably a big Stanley mug of water. No, if I didn't do it, I don't work in the salon. So maybe if like I needed, you know, I need to do payroll, I need to ship out scissors. I know, but you do like hair. Bring the checkbook. No, I do. So I'm just, you know, I'm always fascinated by what your brain does. See, I've heard to that thinking, like that list, I was like, if I had to go somewhere outside of the salon to do hair, what would, and I had like a small bag, what would I put in it? Yeah, that's good. To make sure I can make everyone happy. Well, the bag is one thing, so... Nope. I'll wear cargo pants. Can you guys comment and let us know what your five things would be? I'd like to know. Today's episode is sponsored by Mevo. Mevo Entour, hosted by Mevo Salon and Spa Software, is an in-person series of beauty and wellness business conferences spanning five major US cities in 2024. Mevo Entour, welcome spa and salon owners and managers to learn from some of the industry's best network with like-minded professionals and walk away with newfound ideas and inspiration to implement in their businesses. Upcoming conference locations include New York City, Los Angeles, Chicago, and Dallas. The conference series includes all-day events full of peer-to-peer networking, interactive strategic sessions on maximizing profit, creating unforgettable guest moments, overcoming industry challenges, and more. For more information about Mevo Entour or to register for an upcoming conference, please visit mevo.com slash mevo-on-tour. Scary hair moments. That's where we're going next. I got it. A time in the salon when something wasn't going right. I got a doozy. How'd you overcome it? How did you overcome it? Is that weird to say that? No, I just can't wait to hear them. You know where that came, where that hit in my head? It's because of Sheed. When he's like, I had to overcome everything. I don't really mean like, overcome. I mean, like. Oh, no, if it's scary enough, you need to overcome it. All right, I can't wait to hear this. All right, go ahead. Mine was, Matt, you were there. It was like 10 years ago now. And I had this client at dinner here for a while and she was just always a blonde, like very light, pale blonde. And she comes in and she wants like, Nicole Kidman Copper. And I was like, perfect. I got the perfect formula for that.  So I put it her roots and then I had to do the ends. And I just forgot the really important step of dampening the ends before you pull a copper through. Because if you've ever seen copper hair color when it's processing, it is purple. And so when I washed her hair, it was about shoulder length, she had beautiful copper roots and purple hair. And she was cool. She's like, well, if this is what we were going for, I would love this. I'm like, but it's not. So we go back, I take her back into the shampoo bowl and I'm like freaking out. Like this is not a thing that needs to be happening. Like this woman is in her fifties, like she's not gonna, this can't be purple hair. And it just, I mean, I was trying everything. We were doing, you know, shampoo and bleach mixed. I was trying color remover and it just was like, not really working. I remember at one point I was able to get the purple to turn gray. And I think that was when I panicked the most because I came out and I was like, I can tone any color, but you can't tone gray. Like once you get gray, that's, you're screwed. Actually the perfect description of the color. You know when you hard boil an egg and you pop the yolk out, that color of the gray outside, that's what color her hair was. I was in a full panic. Egg should not be gray. No, just the yolk. Mm. So I remember I came out and I'm like sweating. We're in this for like two hours deep now. And I tell Matt and he's like, well, this gloss is what I use when you need to fix anything. And I tried it and thank God it worked. Like I had lifted her hair enough so that this one, it was a semi-permanent and it kind of leveled it out and got it back to what it was before I even started doing anything and she was okay. She was fine, but it really, I think overcoming it was just not giving up and just realizing like this has to be fixed. And collectively we have the knowledge to do this. Just don't panic and like, you know, do something that you can't come back from. Like, let's just make it dark. Like perseverance. I think that's like the thing with this industry and really it probably anything that you do, but we talked about this a couple of episodes ago, but like the confidence of just like, it will be okay. You just gotta go back to your knowledge. And it's something that we're also kind of in our personal life talking about like with, with Hayden and stuff, like just being, the more you know, the less scared you get about things and like, and how you can handle those situations or whatever. That was us talking about it because I told Hayden that the other morning. That's what I said. Oh, I thought you meant on the podcast, sorry. No, no, that's what you were saying to Hayden like with the other day. Yeah. Yeah. So it's just like, it really goes with everything in life, but like the more you learn and the more you consume with understanding what your, what your thing is, whether it's hair color or whatever it is, like. You're less nervous. Yeah. And you can handle those situations. So like somebody that's in school right now, maybe in beauty school or whatever and you feel like you're making those mistakes, it's actually a good thing because you're building up. Yeah. What to do the next time. The reason we knew what to do in that moment was because it had happened before.  But that's a good one.  Oh yeah. 9RB. That was. 9RB. Yeah. Champagne. You're fix all. Yeah. I learned that from Colin. So that was at a hair show. It all rolls down. Yeah. Which is actually kind of a cool thing if you think about it. Cause if something just kind of took a little too much and you add something with like a very light peroxide, like a 7% or whatever. And it's just going to pull it. It's just going to open the cuticle just enough. To let what we didn't want slide out. Yeah. And that 9RB just kind of gives it that little bit of deposit too. Now mind you, she made a huge scene when she left. Cause I don't know if you remember that part. She was fine with the color, but I felt bad that she'd been there so long.  And it was a little frizzy. Yeah. And then she made such a scene in the salon. Like. I kind of remember this. This was a long time ago. It was. You chased her out the front door because of the scene that she made to like try to calm her down. Like I could do a haircut for free. And she's like, I'm never coming. I was like, okay. Well, that was somehow a success. Guys. You learned a lot. Yeah. That's never happened again. Positive. Do you have one? I mean, I kind of do, but it's not like, I don't know. I feel like it's going to go against what you all just said about. That's okay though. Learning and knowledge and like all that. I just gave up. Sometimes you can't do immense hair again. Nope. Sometimes you just can't. You've got to know when to hold them and know when to fold them. Literally. Fold it real quick. Wait, so you, it was in a men's cut? Yeah. My grandfather was here. And we, he was at home and he just wanted a haircut. I was like, yeah, you know, been working on it. I think I was living here at the time. We were working on it. And I know that in the salon, it was taking me like almost two hours to do a men's cut with clippers. And so I started it.  I could go up a little more. There's a mistake right there. And his hairline started. Right here when I was done with them. So after that, I was like, yeah, I think that's it for me. I don't think I need to, you know. Do them ever again. No, that's okay. So, yeah. That's an okay lesson too. It was like your first probably ever. Yeah, you were so fresh into it. But I still like, I've worked on clipper work and I still just don't get it. Like it's hard for me to see. But it literally, like visually, it's hard for me to see. It's just doing it over and over and over again. Like it's, because I was the same way. Like I shied away. It terrified me. It was years before I was comfortable doing a short like clipper haircut. And then eventually it's like, you learn a little trick that works for you or cause there's no one size fits all with that kind of stuff. Like once you realize like, oh, when I get to this part of the head when I do this, it usually works out. Like it's, you just can't give up. Don't practice on me, but like you can't give up. I know I actually wanted to ask you to clean my hair up the other day. I'm proud about that story. I'm just kidding. And there goes the twinkle in that side. No, I would totally, I would totally like it. Matt, what's your horror story? I mean, I know one that doesn't have anything to do with hair. Yikes. That's a spilt of tea. I thought you just get, I know. The bath. Oh, that was bad. Nothing's good. Oh wait. Remember that time in the bathroom that you failed? No, remember the time the bride was crying in the bathroom and wouldn't come out. I never did a bride again after that.  No. Oh God. There's so many. There's so many. No, there's not that many. Let me tell you one that I, where I messed up though. Oh, I forgot the picture. We'll bring that picture. That was a mess up, but we're gonna, I'm gonna keep it in the salon. That'd be the thumbnail of the episode. Yeah. I was assisting and I don't even know if Sam knows that this happened, but when I was assisting.  No, I almost did that in beauty school, but this one, I was ironing his client's hair. I was finishing it and I was hitting it with a flat iron and I. 450 degrees. 100%. It was 450 degrees. And I had, you know that tool belt we would wear with all the scissors in it? Well, I left it on my station and I was setting my iron down in between getting the sections or whatever. And I set the iron on my tool belt, which had a vinyl belt. And the belt melted onto the iron and I grabbed the iron and I went into her hair and it smeared black plastic all the way down her hair. Like, and it just got hard right away. It was like. That's amazing. It sounds like a superhero movie. Thank God Sam was out smoking or doing something. Like he was not in the building and I was finishing his client. I was like. So that's a learning moment for him. Never to leave your assistants alone. Yeah. So I ironed it again and again. What? I was trying to melt it out. Oh. It was in the back. Wasn't it still on the iron? So no, it all went onto her hair. And so I kept ironing over it and it kept melting and like kind of getting further down. Your thought process is fascinating to me. Then I moved on because I didn't want her to notice that I was doing this. So I moved on to the rest and I kept going through and then I would come back to it. I just did it again. By the end, I finally kind of got it out. All right. Oh, OK. But it was, I mean, still kind of there too. But it. So that. Never again. Did I do that? You be dazzled her hair. That reminded me of one, Matt, that I don't know if I ever told you that I did because I was working for you. Similar kind of. I was doing a bridal party. And I was like the maid of honor. And like we with Paul Mitchell with all the chopsticks and everything we do, the chopsticks is real cool. So I was in my phase of like spraying the chopstick with hairspray and slicking the hair down to get flyaways. But I had been using this chopstick for a very long time. And so I spray and this girl was very blonde with her updo and it was done. Like I was just getting the finishing touches. I spray it.  And I'm in a hotel room. It's like we're here. We're like, oh, let me wash this. Thanks. There's no mirror really. Yeah. So she can't see my face as I realize this. So my reaction, like I tried to pick at it. It's not coming off. And I was like, so I think the flower should go over here that you want to put in your hair. I just covered it with the flower and sent them to the wedding. No idea how that turned out. This podcast episode is going to stop everyone from calling. But I listen to your podcast.  There's no more people driving in two hours. Every profession. Yeah, so we're just willing to tell it. We are here then. Yes. All right, let's let's do trivia. The current score of our trivia is two Christina, one Brian, one me. Goose egg, Carly. Zero Carly. This is Carly's day. I hope my trivia question is going to be how many music. I'm into it. What did you say, Carly? I said when it finally gets to me and my trivia question, I'm going to say how many times did Carly change her hair colors and starting this podcast? Three, right? So, yeah, yeah, I went. Yep. Now I got to go back and watch it. I know that that was my point by the time you get to ask it could be more. Exactly. Never know. OK, so I was trying to find the question that I that's OK. Sorry, we're just grooving over. Yeah, no, I hope everyone at home is dancing, getting ready for their Friday or Monday whenever you're listening to this. I'll just do a different one. OK. OK, OK. We didn't know what the first one was, but. All right. Hit us. OK. It is possible that the mullet has been a part of life right from the beginning. One of the earliest known examples of the mullet can be found on which famous sculpture. Are you tired of the same old challenges with your shampoo, conditioner, face wash? Well, go check out my friends at formulate.co slash Matt Beck, get a customized formula.  It's going to help figure out anything that's going on with your hair or skin. So don't put it off any longer.  Go check out formulate.co slash Matt Beck. And we're back. Hey. And Brian thinks he knows. I would guess. Is it Michelangelo's David? Oh, all right. Nope. OK. Damn. All right, Carly. Billy Ray Cyrus. The sculpture of my own. Right there. This is how this is how bad I am. I'm like, I don't even know what these sculptures, the only one I know of are probably super racist people or Nick Coles. It is so you might have an advantage here. I thought you were going to say like Rocky. Oh, no. So the great Sphinx is thought to date back to somewhere between. Four thousand, five hundred and ten thousand years with the short. At the front and long at the back hairstyle, clearly visible. There's also evidence of the mullet in many ancient civilizations, such as the Vikings and Aztecs. Wow. I believe that.  So because all I can picture is like a headpiece. Yeah. Yeah, I have to. I'll put up a picture of it when me. All right. So now what? In the final, but zero zeroes. So who asked the question? So Christina again, probably. So I get the point. No. Oh, OK. That would be good, though. That's not a bad rule to put in, but not this time. But next time, you can stomp everyone. I'm already winning. If you stomp the group, you get the point. And then that way, people that ask the question can also get a point. Because I'm winning. So we're going to come up with that rule and it's going to happen next week, but I get to answer. I get to ask a question again, but I don't get the. I don't get the point this week. And I stumped you all. I feel now. Hey, that's fine. I'll give you all like a head start. I was going to say I give you like a little. I know how competitive Christina is. Yeah. So next week, it is going to be the most impossible question. How many hairs are on my head right now? Or it'll be maybe, maybe I'll just go with one that I think Carly might know. What's Carly's middle name? Should we make the question? Oh, everyone knows. Multiple choice. Well, if you want, but then whatever, I'm not scared. Carly Louise, I'm scared. I like, I feel like I'm never going to know any of them. Louise, Louise, Carly Louise. I mean, it's got a really, it sounds like it's got a mullet. Carly Ray, did anybody in the chat get that? Because she's a ray of sunshine. No, but they I don't, they weren't answering, you know, what Carly George, nothing. They're just saying hello, love it. Are they talking to each other? Like they're talking about what we're talking about. Oh, OK, cool. All right, love that. Dyson, back in the news. Oh, yeah. Do we throw that up? Yeah, let me click on the article. Here is the. Oh, geez. There we go. Here's the look at their new blow dryer, which looks like the old blow dryer, but it has a different backing to it. They say it's a little bit smaller. And they're really leaning into this blue and orange. And I think it just makes it look cheap. I'm having a hard time with the blue and orange, too. And then it's teal and the other one is teal and some. But some of their colors look good, but this blue and orange combo just makes it look like a toy that is not worth seven hundred dollars. I was so it's five hundred dollars, right? Yeah, but the the other one, the professional one, the other one's five seventy five or something. Right. I don't know. OK, you're just talking right out of the one. I'm talking about tax, Matt. Like about seven hundred bucks, wasn't it? The air. Yeah, yeah. The air wrap is close to that. I'm not buying mine in Delaware.  Don't you remember this about Dyson? That's all things in life. Never ever going to sponsor us ever because but we do talk about them a lot.  I'm not. Yeah, we're not. Yeah, we love this. Please let us be a name. That's a joke. Sarcastic. So the I kind of went all over at first. I saw this. I was like excited because I was like, I like this blow dryer better than the pro looking one. In my opinion, I don't that little. It looks like a candy cane and I just want.  Then I started reading about it and I was like, I don't know if I want my blow dryer telling me I get it for a consumer like as it gets closer to the scalp, it has a safety thing and it calms the heat down or whatever. But I don't know if that's actually what I want. Well, that's what I'm making it for us. But right, I think they're starting to lean into like they're diverging their stuff for us and stuff for consumers. Yes, like, you know, the old question of my clients asking, is the blow dryer worth it? I mean, for me, yeah, I don't know. But now it's making it something. Yeah, because I completely agree. Like it calming the air flow would just piss me off all day because I do what I do the way I do it and just let me do it. But I can see that being really good for people at home that maybe you're not expert blow dryers at protecting their hair. And one of the best features about this to me personally is when you set it down and shuts off. That's cool. When you pick it up, it turns back on like that for anybody doing hair at home or like I like to as a professional, if you're blow drying, I love that this is like my blow dry form.   I don't hate it. It's that's obnoxious. But like, you know what I mean? Like I if I could just set it down and it shuts off and then pick it back up and we're back to work. It's super efficient. And why doesn't the I don't think the pro one does that? No, but that would be awesome if it did. And I don't know. So like if I can turn off the smart system of the or it's not that big of a deal, the scalp thing, I might actually go with this one as opposed to the pro one because I like that feature of being able to set my blow dryer down. So let's do that. I'll go pro. You go that one. OK, deal. I'll do the candy cane. I'll put it in my pocket. So this comes out sections. It doesn't look like a candy cane. It looks like the dentist's tool, the little suction dentist's tool. That's every time I see that. Yeah. Yeah. It sounds like it probably too. What are we talking about? What it looks like. The other are. Yeah, the other one. The pro one we were talking about. It's right here. This one. His hands kind of blocking the curve, but it just it's just a tube. It just curves around like that. But you're right. It looks like the dentist thing. And it probably sounds exactly like that. So nice. So, yeah, that's I don't know which one of you guys feeling like you're yet, if any, if none, like what are your guys's thoughts in the chat? I want to know what. Yeah, five sixty nine, Brian. People is the pro. OK. And four ninety nine is this one. So and it comes out in May. Have they said when the problem comes out yet? I'm on the list for the notification, but I'm not seeing that. But maybe they've announced it somewhere. I haven't seen that yet. But I can't wait. That was so weird in my ears. All right. That's what she said. All right, it's time to go. But we got to spin the wheel. So if you want to spin the wheel, let us know in the chat right now. Spinning the wheels, basically your chance to win something from our online store shop FSE dot com scissors, combs, tri-raiser, EVO razor, all that stuff. We got Meebo on the board. You could win a trip to one of their upcoming conferences. And then also Minerva beauty dot com is given away, I believe, still a Thera gun from their website, but they have a ton of different salon furniture and then also formulate dot co slash Matt Beck. If you guys want custom formulations, they're giving one away on the wheel. Brian's going to give this thing a spin. Who's going to wait? Wait, we got to see who wins, though. How do you want to pick? Anybody saying anything? Are we communicating? Bobby Jeffries, spin the wheel. All right, Bobby, let's spin the wheel for you, Bobby. And it is. Come on, that's a seven on one. That was part of my five. Oh, yeah. Oh, yeah. Seven oh one comb. Honestly, Bobby, you could take a look at our website and pick any comb that's in stock on there. And email us matt at free salon education dot com. Give me your address, phone number and full name and what comb you want, and we'll send you out a brand new comb. Gorgeous. Wow, that ended like perfectly that. That music, that's your that's your radio. Your timing there. Great show. A grade. Yeah. Great call on having more conversation in the show. Thanks. Yeah. Think, you know, it's a podcast, so it's important. Yeah, last week with the videos, I was like, this is not what this is hard to explain. Yeah, let's explain what's going on in the video. Yeah. Yeah, I liked it. Did you guys like it? Let us know in the comments. Make sure you subscribe. Subscribe. Subscriber. Oh, I do have a quick question for everyone. If if they're listening, if they could let us know, because next week we're going to talk about brands and kind of like what brand you love and why. And also, do they offer perks? Yeah, like education, education points towards retail, anything back bar, like whatever, whatever brand you feel because we're we might be shopping around. Yeah, we know a lot about the different brands, but I want to know the inside of more or less customer service and their and how you're treated and, you know, what your money kind of gets you. Yeah, just curious. Yeah, let us know. What brand do you use? Do you like the education? Do they have perks and points and all that? Yeah, cool, cool. All right, guys, subscribe to the channel. Follow us on everything. Follow Brian, hairstyle, Carly, hair by Carly C and follow us. Everything at Freestyle on Education makes you subscribe to the podcast and the channel and hit that notification bell so you get alerts every time we go live. Thank you guys so much for joining us. Have a great week weekend and we'll see you guys on the next show. Bye. Bye.


Hi, everybody. Happy Tuesday. I'm Joe for jaspyscasebreaks.com, and that is 2019-2020 Panini Contenders Optic Basketball 2 box. Pick your team number 105. The last two boxes of that inner case that we popped open, the next two boxes will be from that second inner case from the master we opened the other night. Big thanks everybody here for getting in on it. Appreciate it. Rex with that double last spot mojo. Thanks, Rex. So he's got to requisite two teams to get an entry for that break credit. And if you win break credit, ladies and gentlemen, maybe you could put that towards some of the new releases tomorrow. I usually don't tell people what to do with their break credit. It's yours. You can do whatever you want, but it's such a big new release day tomorrow. All right, so the break first before the break credit. Good luck, everybody. All right, we got a nice Steph Curry superstar die cut. Grizzly is taking game two from the Warriors, so that series is tied up. It's going to be a fun one. Warriors and Zihao with the Warriors. Got Luka Donchich, Blue Ice, not numbered. We got Jonas Valenchunis, Silver for the Grizzlies, Danila Galanari Blue, that's to $199 for OKC, that's for Raymond. And the auto behind C. Jim McCollum, Trailblazers Edition is Rookie Ticket Auto, Nasir Little, C. Jim McCollum's former teammate. That goes to Anthony with the Portland Trailblazers. That's eight out of 25 for Anthony and the Trailblazers. Nice flow number there too. All right, second and final box of this intercase. All right, there's Donovan Mitchell, and we looks like we've got a randomizer here. Historic picks 10th overall, Paul George Pacers, Anthony and Paul Pierce, Boston Celtics, Victory. So that'll be a randomizer between those two teams. Blue cracked ice, Blue Ice, not numbered. We got Jimmy Butler, Silver. We got Lakers edition of Alex Caruso, missed that guy. And behind Triple J is Rookie Ticket autographed Kobe White for the Chicago Bulls. Greg Dash with the Bulls. Bulls were picked up pretty late too. Played some minutes in the playoffs. Showed some signs of maybe doing what he did his rookie year. All right, thanks everybody. Let's do some randomizing. Let's give away some money. Let's see where that dual player card goes. So let's go to random.org. There's some new dice. And then we got Pacers, Indiana and Boston right there. And then for everybody here, if you bought at least an even number of teams, half of those become entries for some break credit. So Anthony bought six teams, that's three entries. Brian bought two, that's an entry. Corey only got that one. Greg got two, that's an entry. Canard got two, that's an entry. Mark got three. Two count for the promo, still an entry. Oliver bought two, that's an entry. Raymond bought two, that's an entry. Rex bought two, that's an entry. Stephen flat got two, that's an entry. Victory got two, that's an entry. Zihao got four, that's two entries. All right, that's a 14 spotter. So we got Anthony, Brian, Greg, Canard, Mark, Oliver, Raymond, Rex, Stephen, Victory and Zihao. Nice. All right, and we'll put that in another blank list right here. We'll use one dice roll for both lists. First, the dice roll is one out of three, four times. So here's the first one right here. One, two, three and a one. Fourth and final time goes to the Pacers. That's gonna be for Anthony. So you'll get this historic picks, two player card. Now the break credit. One out of three, four times. So it's gonna be the top four after four break credit. $100 each. One, two, three and four. After four we got Stephen, Zihao and Anthony. Congrats to you. $100 each going your way. Oh and Canard as well. Top four. Sorry, check that. Stephen, Zihao, Anthony and Canard. $100 break credit each going your way. Thanks everyone for watching. I'm Joe for jaspyscasebreaks.com and I'll see you next time for the next break. Bye-bye.


OK. So welcome to Cloud Native Life, where we dive into the code behind Cloud Native. So I'm your host, Shahrir Al-Musaike Mital. And you can call me Mital Shahrir. So I am a CNCF ambassador. And I will be hosting tonight, right? So every week, we bring a new set of presenters to showcase how to work with cloud native technologies. They will build things. They will break things. And they will answer your questions. So in today's session, I'm stoked to introduce Andy, who will be presenting on open source policy at scale. So this is an official live stream of the CNCF. And as such, it's subject to the CNCF Code of Conduct. So please do not add anything to the chat or question that would be in violation of the Code of Conduct. Basically, please be respectful to all of the fellow participants and presenters. With that, I will hand it over to Andy and to kick off today's presentation. So let me add Andy. So hey, Andy, how are you? I'm doing well. How are you? Yeah, I'm fine too. So yeah, I guess we can start a session, right? OK, let's get started. Let's get going. So I'm here today. I'm Andy. I've been working in Kubernetes for about seven years now. I'm the CTO at Fairwinds. We build software built on top of open source. So we do policy and governance in Kubernetes. And today, I'm here to talk about policy at scale, but I am also here to talk about all the many different ways in which we can implement policy in our clusters, some of the trade-offs of those, and how some of those scales, how some of them don't scale, and sort of share some strategies about how we've seen our customers deploy policy in their environments. Oh, I should also mention I keep forgetting to add this to my intro. I'm now a co-chair of the policy working group every couple of weeks. And so please come talk to us about policy in the working group. So let's dive into the demo here. Oh, and please ask all the questions. I believe you're going to interrupt me at any point. So let's keep the questions coming. That keeps it interesting. Yeah, awesome. So yeah, let me add those slides, right? Yeah. OK, stop. All right, so I always love to do things as a live demo, because I love to, I don't know, live dangerously, and have the opportunity to kind of break stuff in real time. More is learned from breaking things and fixing things than from just doing a shiny demo. So here I have three K3D clusters. So I'm just running a multi-cluster setup locally. I actually borrowed this setup from the Kube Crash demo that we did earlier this year. Thank you to Flynn for setting up the K3D script. So in the repo, we have a repo under my GitHub. It's github.com. Slash, Suderman JR, slash demos. And we're in the multi-cluster scale folder here. And so there's a create cluster script, which we'll just go ahead and create these three K3D clusters and then set up our context. So if we do a list context, we'll see, well, it's not list context, it's get context. We'll see all of our three contexts listed here. And I have a handy script here that will run KubeCTL commands against all three clusters. So we see we have just the base Kube system stuff running here. And I'm gonna kick off a script here called install Argo CD. And so if we watch that fly by, what we're gonna see is that we are bootstrapping an Argo CD installation in each one of these clusters. So we're creating the namespace. We are applying the manifest slash Argo CD files, which have been templated from the Argo CD Helm chart. We're gonna wait for those pods to get ready. And then we're gonna add some repo credentials from a local GitHub token that we have. And then we're going to apply one manifest, which is called app of apps, which is an Argo CD app of apps, which you may be familiar with the pattern. Basically, we create a folder that has a bunch more Argo CD apps in it and it uses that to sort of expand out and install all the things that we're gonna use as part of this demo. So if we go take a look at the repository, this is again, Suderman JR demos in the multi-cluster scale folder. We have a manifest directory. We see the Argo CD apps, the app of apps pointing at this folder here. And we have a series of other apps. So we have a cert manager app. We're gonna install Polaris. We're gonna install Coverno. We're going to install the policy reporter. And then we're gonna keep maintaining our installation of Argo CD. So we're installing a lot of things all at once. I'm not gonna go through the details of every single one of them. Cert managers really use for managing the certs for the admission controllers that we're going to stand up. But the ones we're gonna focus on today, we're gonna talk about Polaris. We're gonna talk about Coverno. And then we're gonna talk about some other built-in Kubernetes stuff. And so to kind of introduce all of that, I have this table here that I have created and it is mostly complete. But what I realized coming into this was at scale, we have five, six, maybe seven or eight options for doing policy these days. If you go back a few years, Rego and Opa were probably like the only ones out there. And then we added Polaris to the mix and then Coverno came along. And now we have two more things. We have validating admission policies which are coming in the latest versions of Kubernetes. Not GA yet, but it's coming. And then we also have pod security admission which replaced pod security policies which isn't really necessarily policy but it is a way to enforce policies. And so I added that to the mix as well and sort of created this table of what can all of these things do? What can they not do? And then some pros and cons of each one because they all have different ways of using them. And so I think Coverno is probably the most popular one that I hear about these days. Polaris, not super popular. Opa gatekeeper, we're all familiar with Opa and Rego. We're all, people are very happy to complain about writing Rego. I understand that the learning curve can be steep. And so if we look across all of these they all do different things well. Most of them do policy at admission time. Not all of them allow you to view those policies or audit those policies. They all use different languages. So you may be comfortable writing in a specific language or already familiar with one of these and may want to pick that for your policy. Some of them, namely pod security admission, there's no custom policy here. This is just you pick one of three levels and you get a set of policies out the gate. So that may be enough for what you need to do. And then there's this new thing called the policy report CRD which the working group on policy has been working on and released. And so this is now a standardized way for these tools to report policy violations in your cluster. And not everybody supports that yet either. And so I believe open gatekeeper does. I think I missed a check mark in there. I think there's a plug in for gatekeeper to support the policy report now. Please correct me on that if I am wrong. But anyway, I think the takeaway here is there's six or seven different ways to do policy and a layered approach might be the right way for a large scale policy implementation because some of these are good at some things and some of them are not. So in order to demonstrate that we're gonna use this demo environment and I'm gonna show the capabilities of several of these tools. Let me jump over here. So we've installed our Go CD. We should, if we run our Kubernetes, our K.sh script here, we should see each of these clusters all have Polaris and Caverno installed. And additionally, we have enabled via the API server feature flags, the validating admission policy and the admission registration API on each of these clusters. So this is how we enable the new validating admission policy settings on a 1.28 cluster because it is in beta. So let's talk about what that looks like first. So if we look in our manifest policy directory, we have an HA policy and there are two objects we have to create in order to use validating admission policy. There's a validating admission policy which looks something like this. This is pulled almost directly from the docs as an example of how to use CL and validating admission policy. And what this says is for any deployment that upon creation or updating of that deployment, we want to validate this expression. We wanna say the replica count must be greater than or equal to three. Now, if you are super familiar with Kubernetes and deployments and HPAs, you may go, well, that's not necessarily a great policy to have everywhere because what if I have an HPA? If I'm using a horizontal pod autoscaler, I don't need the replica count to be set on this deployment at all. Actually, it's a bad thing to set because it will cause flapping with the replica count. And so this is where we start to highlight some of the limitations of CDL. It can't be context aware because it's done at admission time of a single object. And there's no way to say, okay, only do this if it doesn't have an HPA. So one of the limitations of validating admission policy right there. So we create that object that's being applied by our CD in our cluster. So if we get validating admission policy, that's fun to type, which I typed wrong anyway. There we go, validating admission policies. I'll just grab that. And we look for those. We'll see that this has been applied to the cluster. It's called HA policy. And then we have a second object in our policy folder for HA policy, which is the validating admission policy binding. And this basically says what to do with that policy. So we've created the policy. Now we need to say, what are we gonna do with it? So in this case, we're only gonna warn and we're gonna audit this policy. So this will add context to audit events for this policy. And then it will also warn upon applying the policy. And then from here, you can also actually restrict where this gets applied. So you could say, don't apply this policy in specific namespaces or don't apply it for specific named workloads based on different patterns. So there's a lot of options there. They're all in the documentation, but we stuck with a very basic one for this demo. So what I'm gonna try to do is I'm going to apply a manifest and we have a folder called demo here. And I'm going to apply that deploy good.naml in the, I'm just gonna do it in the player's namespace because I know that namespace is available and it works. And what we're going to see, oops, can't do that namespace, that's all right. We're going to create the namespace demo and then we're gonna apply that manifest into the demo namespace. We are going to see a warning come up from our admission controller, hopefully. There we go. So validation failed for the policy, AJ policy with binding, failed expression, replica count must be greater than or equal to three. So you can start to see we can very easily and quickly with native Kubernetes CRDs, which will exist in later versions of Kubernetes, very quickly deploy policies that prevent us from doing whatever it is that we want. Perhaps we want to enforce that everything has a label that is for a specific team, something that's very common for cost allocation and also understanding who owns what in your large scale Kubernetes deployment. So that's CEL, that's how you get started with that. And I think it's gonna have a place in a larger policy strategy where there are some things that just shouldn't happen anywhere and we need to get that policy in place in the cluster as soon as we build all of our clusters. This is just the base level. Now the downsides, it can only apply to single objects and we really have no way of auditing existing objects in the cluster with this policy. So this is sort of a only at admission time, we can see it in the audit logs if you have those going somewhere, but that's really the extent of what it's capable of doing. So that's the first strategy that we see which is validating admission policy with CEL. The second one that we're gonna talk about here is the, or the next one we're gonna talk about is pot security admission. So this is a very straightforward and easy way, even easier than validating admission policy to restrict certain things in your cluster, but it's very inflexible. So if we look at the manifests for example, the, well we're gonna look at our cert manager namespace here, we've added a couple of labels to our namespace. So there's a pod security Kubernetes enforce and a pod security Kubernetes.io slash warn. And so we're going to enforce the baseline pod security admission policy. We're gonna warn on the restricted one. And so there are three levels, there's restricted baseline and privileged. And I think that's the only three. And they get, they're increasingly restrictive. So baseline is what it sounds like, it's a baseline of security requirements and restricted goes a little bit further than that. And we can see that in action, if we apply a namespace YAML for the demo namespace. And we see, we have sort of a similar setup here, but we're going to enforce the restricted policy here. And actually, let's go ahead and show it with what we were just talking about. So we're going to enforce the baseline policy and we're going to warn on the restricted policy. And we're going to apply this demo privileged manifest. So this is a deployment that is privileged. I think it has capsaic admin, I think it has basically got all the permissions I could possibly give this pod. And so we're going to get some warnings that we would violate the restricted policy or warning on that. And then we also see our CEL expression here as well. But the host network is true, the containers privileged, allow privilege escalation is not equal to false. There's a whole laundry list of security problems with this that are now just automatically being warned about in the CLI. And because we actually have the baseline security, we will see that the demo deployment for the demo privileged actually isn't running any pods. So if we look at the replica set that was created by that deployment and we describe it, what we're going to see is a bunch of events where it tries to launch a pod, but we see that pod security admission controller failing to create that pod. So this is a very straightforward way to very quickly get some security requirements into your namespaces. Downside here is there are no exceptions to this. Like once you've labeled that namespace, you can't write an exception that allows a deployment to be created that violates these rules. You can't change the rules. All you can do is move between those different tiers. And so this is potentially, again, a very easy way to start down the policy path, maybe have some baseline policies that get into your app namespaces or things like that. But it's not really a full holistic strategy for deploying policy because I can't do exceptions. I can't see this across multiple clusters. I can't audit this. I can check which namespaces are annotated or labeled with this set of labels, but I can't audit the objects already in the cluster with this. So it's really, again, part of a larger strategy for deploying policy. I'm gonna have a quick drink. Please keep questions coming if you have them. Post them wherever. Yeah. No questions, all right? Still no? Yeah. Okay. I will keep moving on then. So we've talked about these bottom two. We talked about positive security emission. We talked about validating emission policy. I think the next thing that I'm gonna talk about is Polaris. So with Polaris, we have, it's fairly straightforward to deploy. I've called it simple here. It's a single deployment in your cluster that has access to audit the cluster. There's a CLI associated with it and it uses a single centralized config. I think there's pros and cons to that. So I put it in both columns here and it does support custom policy. It has a dashboard which I will show you and it supports, all of its policies are written in JSON schema. So some of us may be familiar with that. It's a relatively straightforward syntax to learn. And as of this moment, it does not support the policy report API, but I believe we will be looking at adding that in the future. So let's talk about Polaris a little bit. We have in our manifest directory templated out the Polaris deployment via a home chart. It includes both validating webhook configuration and it can do mutating webhooks as well. There's a deployment for the dashboard and there's the deployment for the controller and the webhook itself. And when we deploy Polaris into a cluster, again, we do that via a centralized config. So we can take a look at our Polaris configuration here and I'm gonna make that an animal file so we can get some syntax highlighting here. So we have a whole lot of checks built into Polaris. You can control whether they're ignored, whether they warn or whether they're dangerous or block in the configuration here. And then we can add our custom policies. So as an example, I've added a custom check for image registry that says your images have to come from specifically allowed registries. We're targeting containers with that. So this will apply to any controller that creates a pod that has containers in it. You don't have to write anything fancy for that. We just include that in the JSON schema or sort of extending JSON schema here. And we say that the image has to be any one of these reg exits. So this says, they've got to come from several Quay repositories or several Docker, US Docker.package.dev or GCR. So fairly straightforward policy there. We have additional ones for resource limits and constraints, so we can target the container. And then we kind of give you- We have a question, I guess. Awesome. So the question is like, how can we map the policies to CS benchmarks? That is a great question. That is a great question. And there's a few different ways. And as I get through Polaris here, I will talk about that a little bit more. But a lot of the different policy engines have policy groups that they map for you. And so, they will sort of say this set of policy maps to the CS benchmark, this is how you do that. One of the things that we discussed just this morning in the policy working group is potentially putting together sort of a CNCF blessed version of the policy packages for mapping to those benchmarks or publishing specific mappings to specific policies. And it's a big topic right now for policy because you go from policy to compliance and they're two very different things, but they work together in tandem. And so, I will say, I believe Polaris, we map the CS benchmark specifically in our checks. I don't know how we specifically say that, but we do say we cover the CS benchmark. So, and then we've also got the NSA checks as well, but we don't necessarily have a way to map those just yet. We do in our commercial product. And I know several other commercial products do as well, but open source hasn't quite gotten to that point yet. But a great question and something to think about as you're building your policy strategy is how are you doing that mapping and where do you keep your policy? How are you doing that mapping and where do you keep that mapping? So, let's just keep going down the road with Polaris. We've got our custom checks. We've got another one here that says you can't have host path mounts because those are dangerous. And then we have exemptions. So, this is where we start to get into a more complex policy strategy because there are things in your clusters that are going to need host path mounts. There are things that are going to need host networking, particularly CNIs and various other storage controllers and things like that. And so, we have the ability to say centrally from this central config, which I'm deploying across all of my clusters via GitOps to say these things are allowed to violate these rules. So, we have things like the local path provisioner which is common in my demo clusters is allowed to have host path mounts because it needs to do that because that's its entire job is to create host path mounts that map to storage provisioner. So, this is kind of the next level up. We need to look across all of our clusters and see what needs exceptions and figure out how we control those exceptions. Polaris allows you to create these exceptions via annotation, but that creates a security problem where someone could escalate their own privileges by using that annotation. So, we have to restrict the use of that annotation or we have to use a centralized config in order to do that. And so, when we're talking about deploying this at scale across multiple clusters, not only do we have to have a valid list of exceptions but we have to think about how we're letting people use those exceptions. How are they approved? In this case, we have our Polaris config in our manifests here. So, if we go to Polaris and we look at the Polaris config map, the settings are all right here. So, we could have a process by which people request exceptions by making a pull request into this repository. That could be our exception, you know, process. We can document that. It's tracking git. We can have approval processes. That's one way to have this sort of workflow by which we add exceptions. And Polaris does allow us to say only get exceptions from the centralized config. We can also take a look at the Polaris dashboard. So, hopefully this is working. We'll see, all right. Right now we're filtered down just to a single namespace. So, you could see, you know, if I am the owner of the demo namespace, which, I think we jumped clusters here. Cluster, am I in here? I'm in the EU cluster. So, that's this one here. We can filter down to namespace demo. And I'm the owner of this namespace, maybe. And we can look at just the events for that namespace. So, you could provide this to your developers or folks that are deploying to the cluster and see these warning policies in this kind of nicer dashboard. And then the last way you could implement this policy across all of your clusters, you know, in this case, we have a single repository that's controlling all the YAML for this cluster, right? It's this manifest directory, you know, all of the YAML is here. And so, we could use the Polaris CLI to audit the YAML in this cluster. We could put that in our CI CD pipeline for that and then sort of warn or block on these checks before they even get into the cluster. And so, we're shifting the responsibility for managing, for responding to these policy violations to the left. So, if we do an audit path manifests in this directory, we use, we can use the same config that we were just looking at. So, you know, we can use the same one that we're running in cluster. We can use on the CLI. And we just want to format that a little nicer for the purposes of the demo. You can see all of these warnings directly in CI and we can control the behavior of that, whether it fails or succeeds, passes the pipeline with this CLI. And so, we've now run the same policies, both in CI, in cluster, and they run at admission time. So, we've got all three places where we're checking these policies and we're using one centralized config to manage all of those. And so, when you are, you know, looking at scaling policy up across multiple clusters, across multiple teams, across multiple deployments, having multiple ways to interface with that policy is super important. So, that's Polaris. We've covered CEL, we've covered pod security admission. We've covered custom Polaris config, the CLI. Again, we have in the Polaris audit command different ways to control exit codes. So, we could say, you know, you have to get a certain score, you fail if there's any danger items. And then we can sort of customize that, however we want to enforce these policies across our clusters. And then the last one we'll talk about, which I know lots of folks are fan of, I'm a big fan of as well, is Caverno. So, we have in this cluster, in our manifest directory, we have a policy app, which we looked at earlier. That's how we deployed that validating admission policy. There are a few other policies as well. So, we've got our Caverno policies in code here. We're managing the policy as code or deploying to the cluster with GitOps. In fact, we're deploying to all three clusters via GitOps. We have this Caverno policy. We don't want to deploy stuff to the default namespace. Pretty common thing to not want to do the default namespace can't be deleted. So, it's a little bit of a difficult thing to work with and you don't necessarily want to deploy stuff there. So, we have a bunch of metadata about this policy and the Caverno policy gives us this match and exclude sort of rule set. They've got their own syntax by which you write these rules. I'm not going to go in depth on how to write Caverno policies. They have a massive library of policies available in their GitHub repo, some of which map to the benchmarks, to our earlier point. Actually, if we go look at the Caverno documentation and we go to their policies section, they have, well, they actually have the specific Sys benchmark in here but they do have groups of policies mapping to different things. So, you can take a look at all those policies and see how they map and they've even recreated the pod security standards that we talked about earlier right here in their policies. So, if you did want to just one policy engine, you could and replicate the things that pod security admission does. And so, we apply these policies as Kubernetes objects. So, if we get cluster policy across all of our clusters, we'll see that we've used our GitOps controller, Argo CD, to apply the same policies across every single cluster. And so, we have a very consistent experience across the clusters, but given the abilities of GitOps and things like that, we could kind of tweak which policies go into which cluster based on how we organize our deployment here. Coverno also has the ability to just audit or enforce, same with Polaris where we did warnings versus danger items where we're blocking them or we're just alerting on them. We have that ability with Coverno as well. And then, Coverno also outputs what's called a policy report. And so, this is where we start to get into the ability to audit across all of our clusters. We get a summary of all the objects that are passing all of our policies, that are failing our policies or that have other issues. It's kind of a verbose thing, but if we take a look at the policy reporter, which is this other open source project in the Coverno repository, it allows us to view these policies and what's failing. So, nothing's actually failing right now, that's cool. If we look at our policy reports, we can start to see all the things that are passing. So, all of our namespaces are passing these things and we can take a look at what policies we have. So, for example, I talked about requiring a team label. So, we have a require labels policy. It's in audit mode, which means it's only going to show up in these policy reports. It's only going to warn us that we don't have that. And so, we can go through and make sure everybody's using that label. We can take a look at the details of it, what's passing that check and what's failing it. In this case, again, we have nothing failing that particular check at this time. Although, if we go look at the EU cluster and we go back to dark bone, we might have something failing. I'm not sure if we do or not, we do. So, I deployed those things into the demo namespace earlier and we see now in this cluster, where I've gone to the EU cluster that I've been deploying into, we see our failing checks here for requiring the team label. So, this deployment does not have the team label. So, we have our policy violation there. We can filter down to different namespaces, just look at that demo namespace that we care about. And so, another way to provide access to these policies to your developers that might be using them or running into being blocked by these policies as we saw earlier. So, if I, for example, edit this deployment and I say put it in the default namespace, we will see that we should get blocked because Coverno has disallowed the default namespace and we can't deploy that there. So, you have to decide what's the right time to expose this because this isn't a great experience for me as a developer. I go to deploy to a cluster and all of a sudden I can't. Well, that's too bad, right? So, maybe it would have been better if we had had something running in our CI CD or perhaps a pattern for deploying these applications that doesn't let you know, that says upfront, here's your standard deployment. It needs to go in a namespace. Here's your namespace that you have. All right. Do we have any questions, folks? Bring the questions in. I guess what keeps these things interesting. Yeah, we need questions now. Folks, some questions. Yeah, you can point to, I guess. Do you have any questions for me? Not yet, let's go. All right. All right, we will keep going. So, what else have I not talked about? So again, like I said earlier, we're using our ROCD to deploy these. The nice thing about this, and I'll have to go get my password again. We take a look at ROCD. This is a great way to deploy across all of your clusters. So, we're using ROCD. It's pulling in all of those directories that I showed earlier in that manifest directory. And so, if we look here at policy, we've got the validating admission policy that we looked at earlier. We've got the validating admission policy binding. Then we also have our caverno cluster policies. And so, we're actually running this ROCD in the same way across all three clusters. It's pulling from the same Git repository. So now, I have a way to control all of my many policies and make sure that they're deployed consistently across every single cluster that I'm running. And if I go look at the ROCD dashboard for the next cluster, the US West cluster, I'm gonna see that I have, again, the exact same policies being deployed, which means that when I go to the Polaris config and I wanna create an exemption for, something in the, where's my exemptions? There it is. Something in the cert manager name states that's now going to apply to every cluster. And we're gonna deploy cert manager in the same way across every cluster using these templates that are all in this one single directory. And for infrastructure level things, such as policy or cert manager or things like that, this is a great pattern. It allows me to be super consistent across all of my different environments. Again, there's probably 10 different ways to organize this. You could run a centralized ROCD server that pulls from this and pushes out to all of your clusters. And so it's really up to you how you wanna do that, but the key is be consistent, manage your exceptions centrally if possible and enable your developers to modify those exemptions as needed with an approval process as you roll out these policies. I was hoping to get more questions. So they're not gonna direct this. Yes. Folks are quiet. Everybody's doing policy perfectly. They all know exactly how to do it. So the last one that I haven't talked about much today is Opa Gatekeeper. It's a popular product. I have not used it a ton personally. I think the folks find it difficult to write Rego, but once you get used to it, I actually really enjoy writing Rego. One thing you can do with Rego is start to write policies that, and I think you can do this with Coverno as well, but one thing Rego does is it makes it fairly straightforward to do contextual policies. And so one thing that we have in, and we support Rego in our commercial product, similar flavors of Rego work in the open source as well. But if I go and take a look at some policies that we're actually using in our clusters today, we can go into this insights configuration that I have, and we can go into the open directory and I can talk about policies. So we've implemented the no default namespace here in Rego, but one thing that we do as well with Rego is sort of RBAC type things. So you can't tell, basically RBAC says what people can do, right? You can create policies that say, you are allowed to create namespaces, you are allowed to delete namespaces, but you can't specifically say this namespace isn't allowed to be deleted via RBAC. You could say you don't have the ability to do that, but one way to be, like in this case, we might not want to ever delete a specific namespace, we might wanna protect that. So we can write a Rego policy that says you can't delete a namespace or a specific namespace. And so this is something that you can do with Rego that is a nice way to enhance RBAC if you want to be a little bit more explicit about things. And so we can also add things in here, like input.metadata.name equals infrastructure. You can't delete the infrastructure namespace or you can't delete the Qt system, but it's not that you would try, I hope, but you can add a lot of different stuff. So Rego feels a little bit funky because you're basically saying all of these things have to be true in order to trigger a violation. And so it's a little bit different way of writing your policy. And then this is an insight specific policy, so we include this action item that allows you to put contextual information around that. And so that's kind of what Rego looks like, at least in the context of everyone's insights. It's fairly similar to how Rego would be written with Opa gatekeeper. And so there's another one here. It's in the resources directory. One thing you can do as well is comparisons. So in this case, we have a CPU limit to high, not dot repo, not Rego. And what we can say is that we can start to get a little bit more complex here. And what I'm calculating is the percentage difference between the request and the limit of this particular resource. So we're gonna say your CPU request can't be more than 100% higher, or your CPU limit can't be more than 100% higher than your request. So sometimes you'll run into trouble, especially with memory and CPU limits where you set the burstable amount that if all of your pods bursted to that top amount, you would overwhelm your nodes with that burstable amount. And so we can set sort of a threshold via Rego and say, all right, there's percentage difference and we have all these useful functions for parsing CPU, parsing requests and limits. We round them and we actually do a little bit of math here and we're able to write more complex validations here in this Rego. And so that's another probably benefit for Rego is that it does allow a certain level of complexity that you might not get with JSON schema or with Coverno policies or with CEL. And so always good to evaluate the different policies that you might want, level of complexity, where you can write them. All right, and then one thing we haven't talked about is multi-cluster and so we had our diagram here and all of these tools really out of the box are sort of designed to run in a single cluster, right? You've got your admission controller that needs to be local to the cluster. You've got your dashboard, in this case, the Polaris dashboard and the policy reporter dashboard for Coverno only report on a single cluster. When I was looking at Polaris here, I moved between clusters by just changing which dashboard I was going to. So this one takes me to the one for the US West cluster in my demo here, but it doesn't aggregate them across clusters. And so this is an interesting intersection of policy at scale and all of these open source policy engines. A lot of them reserved multi-cluster functionality for the commercial offering, which makes sense in a lot of ways. So Fairwinds Insights I know does multi-cluster. I believe Normada's product does as well. One thing you can do is with the policy reporter, this actually emits Prometheus metrics. So we could, if we had a multi-cluster Prometheus configuration where we were aggregating certain things across all the clusters into a centralized Prometheus, we could then recreate a multi-cluster dashboard in Grafana with that Prometheus using purely open source. But it does require a significant amount of effort to build that multi-cluster metrics pipeline and be able to pull those metrics into a centralized place. So you have to make the trade-off of, are we gonna pay for something that does that for us or are we going to just build the open source out ourselves? And I think multi-cluster Prometheus aggregation is probably not in scope for our demo today. And it's not, I haven't built that yet. But maybe a future demo we could talk about using pure open source to pull in all these different things across multiple clusters. But again, being consistent across your clusters is first and foremost, and then having visibility across them as second, I think. So. All right. So yeah, so yeah, like we have just one question today. So yeah, I guess. Quiet today, it's December, folks are fighting from the cold, at least in Northern Hemispheres. So. You can see that. I'll give it another couple of minutes. I don't have anything else really to show as far as demo. You can go to the repo and run the create clusters script and the install Argo CD script. If you wanna take a look at all of this side-by-side, it does automatically deploy via Argo CD, all of those various things. So I'll add a quick read me to this later for folks who wanna try out the demo themselves, maybe Tinker with Polaris and Caverno and CEO and validating admission policy and pod security admission all side-by-side because we do have a ton of different ways of doing policy. And I do think a layered approach is gonna be appropriate as we go forward. So we'll probably be expanding this demo here to include, you know, Opa gatekeeper as well and start to explore how we layer all these different things together and what's appropriate for different strategies, different levels of security that you might need in your cluster, different benchmarks or different compliance standards that you need to work with. So lots of opportunity here. Yeah, and again, please come to the working group policy meetings. We always love to have new folks joining and talking about policy and working on the next big thing. Yes. So yeah, that's awesome, I guess. Let's wait one or two minutes for the folks like if they pop up with any questions also. Yeah, all right. Great, so yeah, in the meanwhile, like if there's any link or GitHub repository that you would like to share with the folks, you can share it with us, I guess. Yeah, let me grab the link to the specific demo. Do I just send it? I'll send it to you in the private chat and then you can post it? Yeah, sure, cool. I don't know if I can access the regular chat. I've never done that in one of these. No issues, I can share that for you. All right, I appreciate it. And then we can definitely share the link to our open source policy engine alerts. Put that in there as well for folks to take a look at. And I'll continue to expand that demo out going forward for folks, so keep an eye on that. And then I can always be reached in the CNCF or the Kubernetes Slack. I am SudermanJR, my GitHub username, pretty much everywhere. Okay, so yeah, I think folks have no questions this time, but it was really awesome just watching a lot of terms. So how this thing is scaling works and how you were applying this policy as well. Okay, so I think as folks have no questions, I guess we can end the session, right? Yeah, I think we can call it. Thanks for having me, always a pleasure. And thank you so much, Andy, for being here and just nice having you in the session. Thank you. Okay, thank you. Bye. Okay, so thanks everyone for joining the latest episode of Clownity Life. We enjoy the interaction and questions from the audience. So thanks for joining us today and we hope to see you again soon.


Okay, James Piedmont down here, Royal Hibachi, Royal Hibachi, Guerrero, Rue 46 West, Sutter Book, New Jersey, I'm starting off with some duck and it looks like I got here just in time, Commodore or Jeff Sambello, I think, well, can't be too fussy, you know, you know how duck is, a lot of fat, a lot of bone, but at least I got my choice of pieces, let's see, see what I can find here, ah, you know, what are you gonna do, a little on a bony side, but what are you gonna do, duck is bony, bony and fatty, all right, see what else we got, ah, cock trouble, what do we got here, huh, one of those land ribs, so you got a new thing now, they got covers on certain items, this tilapia fish, ah, you know what, I'll take a piece of tilapia fish, I don't know why they used to call it St. Peter's fish, I have no idea, it's actually an African cichlid from the Nile River, to be honest with you, and then it became popular in fish farming throughout the world, throughout the world, a little surf and turf, ah, I'm not sure what this is though, I don't know what kind of ribs they are, I'll have to go on the other side, got some grilled calamari, teriyaki, okay, you've seen it here before, got some calamari tails and body, tongue tid and tail, the three, the three rules of dating come in our Jeff Sanbello, an old friend Tony used to tell me, ah, by the first date you should be getting tongue, by the second date you should be getting titch, and by the third date you should be getting tail, if you don't get tail by the third date, then you are only destined to be friends, tongue tid and tail, rule of dating, we get the back fin of the calamari, there you go, tongue tid and tail, surf and turf, all right, kind of ribs we got there, oh lamb breast, oh how about that, lamb breast, how about that, whiting and peasants, peasants fish, see what we got here, I'm definitely gonna get some of those, some of that breast old lamb, that's what damn sure, ah, here we go, breast old lamb, sacrificial lamb Jeff Sanbello, sacrificial lamb, I mean I don't know, pretty big ribs here though huh, I think my plate is full, hey you just put out more tilapia, how about that, more tilapia, breast old lamb, all right, what do we got here, squish squash, squish squash again, oil and banchi, french toast, hot dogs, what do we got over here, fried chicken, chicken licking, it's delicious but I can see chicken anytime, breaded fried, butterfied shrimp, not the coconut version, the regular version, ah, you know what, I'll take take a couple, eating that I don't have much room, right, I'm gonna need a steak knife that's for sure, I'm gonna need a steak knife passing through, I might as well get it now, steak knife, okay now, here's a good bird's eye view of my food, right, let me get some lemons for my water, most refreshing drink known to man is ice, lemon ice water, all right, there we go, gonna need some lemons, color coordination, what's that, oh it's oranges, okay, fresh pineapple, where are they, here we go, color coordination, all right, you got that, oh these are the black muscles, ah, not the New Zealand ones, these are the black muscles, okay, the pink ones of course being the female, and the grayish ones being the male, I'd never had them in this fashion before, northeastern cold water black muscles, the kind you usually find with muscles marinara, all right, it's a Mongolian barbecue action Royal Apache buffet, real 46 West out of Brooklyn Jersey, look at all that shrimp, the vapors of life, I'm gonna adjust them by the vapors of life, they'll saute in those omyons, adding a little salt, there are all those veggies and shrimp, a lot of shrimp, the king of all Mongolian barbecues right there, the king is right there, there we go, look at that, there we go, optimum Mongolian barbecue action here at the Royal Apache buffet, even though it's not as packed as it was on Black Friday, but somebody wants a Friday, Friday, what is this, breakfast time here, Mongolian breakfast, Mongolian desayuno, Mongolian desayuno, oh my god, look at that, this is the first time I have this on video here at the Mongolian barbecue station, somebody wanted three eggs, look at that, three wave-ons, they're gonna be an eggstacy, exact eggstacy, when they get the shrimp, veggies, grilled along with the three eggs, and we're not yulking around either people, you know, Jeff same Bella, we're not yulking around at all, this person is going to be a Mongolian barbecue eggstacy, the Mongolian breakfast is what it is, look at that, fresh eggs, bright orange yellow color, look at that, the vapors of life are back again, this guy's the king, this guy's the king, Royal Apache buffet, Route 46 West, Saddlebrook, New Jersey, eggs over easy, or is it eggs over sleazy, that is the question, over easy or over sleazy, I remember when, I think it was Larry Fry and said to Mo Howard, how do you like your eggs, he said sunny side down, but don't flip them, sunny side down, but don't turn them over, I tell you, talk about multitasking, this guy's the king, one of the shrimp got lost, I don't know, don't finish products right there, don't finish products, don't crimp the shrimp people, here come the eggs over sleazy, whoa, one in each dish, look at that, three eggs, three plates, how about that, look at that, there we go, alright that's enough, now it's time for me, a little more vapor, Jeff Sandbell, a little more vapor of life, a little more vapor, alright it's time for a little fruit of the mar here, fruit of the mar, the broth of the sea, look at that, calamari, that's calamari and a cherry stone clam, right, we got shrimp, cherry stone clam and a muskle, right, look at what we got here, well I see a lot of broth man, a lot of broth, a lot of art, look at that golden color, look at that golden color, which means the buttery taste, look at that broth of the sea, look at that, can't be beaten, let's see what we got down here, got some shrimp, uncrimped, got some black muskles, black muskles, it's like slipping out of my tongue, it's almost like it's still alive, look at what's going on here, look at this, let's say that broth looks really good, or is it a Kohlhag, Jeff Sandbello, oh you get another black muskle, love those black muskles with a little broth, a little cock dribble, alright, another crimp, another crimp shrimp, there's a spoon here, what am I doing, I'm worried about using the tongs for it's safe, there you go, beautiful, beautiful sight, beautiful work of art, alright, yeah, oh Krampus where are you when we need you, where are you when we need you unsupervised obese child trying to dive into the ice cream freezer Krampus, oh Krampus where are you, where are you great Krampus unsupervised children messing up the ice cream station, okay before my ice cream I decided to get some fresh pineapple and what looks like a sort of German chocolate cake but I could be wrong but looks good, there's a treleche, latin delight treleche cake which they start to massacre but I'm not in a mood for it to be honest with you, this chocolate cake looks good, I'm not really into icing too sweet for me, so that's about it and then I'm gonna hit the infamous ice cream station, probably get chocolate or chocolate chip mint either way, either flavor, all right we got a little extra mongolian barbecue action going on here, a lot of noodles, some shrimp see one slice of beef, a different man doing it, the other one, I don't see him right now, he's been helping a lot of high protein ketogenic diet, got shrimp, you got beef, you got some mongolians here and there, mostly carnivorous mixture, caramel or jeff cendol, look at that, they call that the atkins ketogenic diet or the paleo diet, look at it, throw that protein, that looks really good, okay we got the vapors of life going, oh he's cutting up the chicken, he should get one of those serrated spatulas that they sell, you know, they easier for him to cut up, oh here come the king, here's the king right now, the king of mongolian barbecue is back, oh look at that, this guy's busy, this is, look at the action here, he works very hard this man, you know, because people are really picky and with the seasoning and sauces that they want on their foods, very high demand, general public occupation, the good thing I'm not doing it, I got no patience for anything or anybody, who's that vodka, oh no I think it's water actually, no I'm only kidding it's water, I'm joking around, this man is the undisputed king of all mongolian barbecue, finish product number one, okay that's it, that's the end of this, actually it's the end of November 2018, this is my lunch buffet in honor of Krampus, in celebration of Krampus, Festivus Feterrestivus in Winter Solstice Eul, here's chocolate ice cream, you think I piled it high enough or should I pile it higher than this, what do you think, what do you think, I got it from the ice cream station, it was a full tub of chocolate ice cream, the full tub, all right beautiful, okay, all right Royal Hibachi, buffet will 46 west south of Brooklyn Jersey, signing off for this Friday have a safe and pleasant weekend people


Abstract the therapeutic potential of ginseng has been studied extensively and ginsenosides, the active components of ginseng, are shown to be involved in modulating multiple physiological activities. This article will review the structure, systemic transformation and bioavailability of ginsenosides before illustration on how these molecules exert their functions via interactions with steroidal receptors. The multiple biological actions make ginsenosides as important resources for developing new modalities. Yet, low bioavailability of ginsenoside is one of the major hurdles needs to be overcome to advance its use in clinical settings. This article was authored by Wong Anis and Lung Kha.


to the course on dealing with materials data. In the process of statistical inference, we are undergoing the sessions on hypothesis testing. So far we have considered the testing of hypothesis with the two sided alternative that hypothesis that mu is equal to mu 0 with the alternate that mu is not equal to mu 0. We found that when the population variance is known, the test statistic is Z which is sample mean minus mu 0 divided by standard deviation over square root n. If it follows, if the population is normal, this follows a normal distribution. If sigma square is unknown, then the test statistic is defined as T which is X bar minus mu 0 divided by sample standard deviation divided by square root n. And under the assumption of the normal population, this T statistic follows a T distribution with n minus 1 degrees of freedom. Then we also found that the sixth step of classical hypothesis testing procedure can also be carried out by working out the probability of type 1 error. And we also went through how to derive the type 2 error as a function of alternate hypothesis mean mu when it is not mu 0. In this session, we are going to consider the case of two sided alternatives. There can be two of them, mu is greater than or it should not be greater than or equal to, it has to be only greater than. So, let me correct myself. This should be only greater than mu 0 and they should be only less than mu 0. So, there are again we are taking the two possibilities under normal population assumption that variance is known and variance is unknown. One sided alternative hypothesis, you have either this or this and we will follow the six steps of classical hypothesis testing. So, let us take the case when sigma square is known, mu is unknown and we are assuming normality that is the population is normal with mean mu and variance sigma square. We have the null hypothesis as mu is equal to mu 0 and mu or the alternate hypothesis as mu is greater than again the error has occurred. So, I stand corrected, mu is greater than mu 0. Here also it will be mu is greater than mu 0. So, then we have the test statistic like before it is going to be x bar because expected value of x bar is mu and then we say that we can reject the null hypothesis that is the critical region has to be such that now I have removed the absolute value x bar minus mu 0 has to be greater than c. So, if you look at the, sorry, okay, if you look at the normal population, this is your mu 0 and there is some sigma here, some value sigma is there. What we are saying is that x bar has to be in the vicinity, but you have to reject it if it is very far away on the positive side. So, actually if it is anywhere far away from mu 0, you have to reject it, but to some extent we are going to accept it. So, we are going to make some limit if it is very far away and this value is what I call c. If it is very far away, then this is the region where I am going to reject it. So, I am saying that x bar minus mu 0 has to be greater than c. So, this is, if I plot this x bar minus mu 0, it has to be greater than somewhere here. So, if your x bar value itself is some larger than this value, then you are going to reject it. So, again our test statistic is standard normal devi at z which is x bar minus mu 0 over standard deviation over square root n which is a normal with a known population mean and standard deviation when H naught is true. And therefore, we come to the test statistic. This is where the difference is, so I have shown it in red. The absolute value is gone. It has to be greater than c dash which is equal to alpha and therefore, probability of z greater than c dash is alpha, then c dash has to be a small z alpha. And we will say that the decision is if the z value is greater than z alpha, then we reject at 0. Let us quickly plot it up. This is a standard normal barrier distribution with mean 0. And we say that we want this area to be alpha. So, z alpha. Actually I should have said z 1 minus alpha because again in the table as I said, z alpha is defined as probability of minus infinity to z alpha is 1 over square root 2 pi exponential minus 1 half x bar x square dx. This has to be alpha. So, if you want this area to be alpha, z has to be z 1 minus alpha and therefore, it is here. Then you reject the null hypothesis, please make this correction. So, anyway I have already shown in the plot. So, if we take the same example again, exactly the same example as before. And now we do the one sided testing in which we take a beam is equal to mu 0 is that is the hypothesis that the population mean is 1110 MPa versus alternate that mean is greater than 1110 MPa. And at present we have found our from our sample the mean value. The sample mean is 1129 MPa, sorry for this mistakes in the slide. So, this is MPa. So, accordingly we work out the procedure. The next step is that what is the critical region has to be x, the capital z greater than small z if H naught is true and then we would like it to be alpha. So, we say that z is distributed as normal 0 1. I think now by now you must have realized what the procedure we are following. So, this becomes alpha which is this has to be 1 minus alpha. It has been calculated as 1 minus alpha I know, but it has not been written correctly. So, we find that this particular value is 1.72 and alpha as I have already written as 1 minus alpha. So, the z value is 1.645 and 1.72 is indeed greater than 1.645 and therefore the hypothesis is rejected. Remember in the previous case we had accepted the null hypothesis in this case with the changed alternate we are going to reject the null hypothesis. I think the mean value has also been changed, this value x bar has also been changed. So, let us take the other alternate. I think you would understand in the other alternate what has to happen before going into the detail. If you are looking at the population distribution and this is mu 0, you are going to reject when this has to be small. So, mu is less than mu 0. So, up to some value you are going to accept it, below that you are going to reject it. If it is very very small you are going to reject it and therefore this value is going to be z alpha because this is what we would like to have alpha and this will be exactly z alpha. So, coming to the point you see that that is exactly z alpha, here I have made a mistake I have totally mixed up the two things this has to be alpha, this is also alpha and then you reject the null hypothesis. If you take the example you can work out that it is also you can work out the example and you will find whether you take a mean value to be say 1108 which is smaller than 1110 and then see if the hypothesis, how the hypothesis procedure works and do you reject the null hypothesis or you accept it. The two sided case when sigma square is unknown, I do not think we need to go through the whole procedure by now because we have clearly seen that under the null hypothesis of mu is equal to mu 0, the underlying test statistic is this, when sigma square is known. If sigma square is unknown then sigma square gets replaced by the sample variance and therefore it becomes a t statistic. So, this is when sigma square is known and this is when sigma square is unknown then it gets replaced by sample variance square. Thus the two sided case will accordingly change to a t distribution with n minus 1 degrees of freedom while this becomes a normal distribution with zero mean and one standard deviation. I do not think we need to repeat this in a totality because it is a very obvious case. So, let us summarize it. We discussed one sided alternate of mean value to be greater than means mu 0 or less than mu 0. In both the cases we found that when sigma square is known or rather in all the cases, we found that when sigma square is known, z which is standard normal deviate which is x bar minus mu 0 over sigma square root n is the test statistic and the test will procedure will follow normal distribution. If sigma square is unknown then the test statistic takes a value t because you replace sigma by sample standard deviation and it follows the t distribution with n minus 1 degrees of freedom. Now before we close the session I would like to repeat or bring out one particular feature here. Remember that x bar that is the sample mean is a good estimator. It is an unbiased estimator of population mean no matter whether the distribution is normal or non-normal or whatever. Similarly, sample standard deviation or sample variance is an unbiased estimator of a population variance. It does not depend on the distribution and therefore these two statistic the z statistic and the t statistic play a central role when you want to test a hypothesis with respect to mean. Similarly, in the next session we will say that if you want to have a hypothesis testing for the variance of the population. So, you want to test a hypothesis which is something like sigma square is equal to sigma not square and what do you think would be the central statistic? It has to be s square over sigma not square and it would be distributed as chi square with n minus 1 degrees of freedom and just as t and z this is going to be the test statistic. We will look into it in the next session. Thank you.


We make decisions based upon the data we have and data is an imperfect science and I think that's the one condition that we must always recognize is if we understand the degree of imperfection or the lack of information we still are making good decisions it's not that we're making bad decisions we're making good decisions it's just our information is less than perfect