A frequency polygon is another way to show the information in a frequency table.
Frequency Polygons. A frequency polygon is another way to show the information in a frequency table. It looks a little bit like a line graph. To make a frequency polygon, you just need to plot a few points and then join the points by straight lines. The reason it’s called a polygon is because the line sort of forms a plane shape with the horizontal axis as one side of the shape: Now a frequency polygon and a histogram both show the same information, but in a different way. Why would we want to draw a frequency polygon instead of a histogram? Well, the most common reason is if we want to compare two different sets of data The frequency polygon is shown in the following figure. Fig 1: Frequency polygon of the distribution of the marks obtained by 50 students in the pre-test examination. From the above figure we can observe that the curve is asymmetric and is right skewed. Graphical display of the frequency table can also be achieved through a frequency polygon. To create a. the intervals are labeled on the X-axis and the Y axis represents the height of a point in the middle of the interval. In a Frequency Polygon, a line graph is drawn by joining all the midpoints of the top of the bars of a histogram.  Figure 1. Frequency polygon for the psychology test scores. A cumulative frequency polygon for the same test scores is shown in Figure 2. The graph is the same as before except that the Y value for each point is the number of students in the corresponding class interval plus all numbers in lower intervals. You should include one class interval below the lowest value in your data and one above the highest value. The graph will then touch the X-axis on both sides. A frequency polygon for 642 psychology test scores shown in Figure 1 was constructed from the frequency table shown in Table 1. Table 1. Frequency Distribution of Psychology Test Score Or, we can say that a frequency polygon is a closed figure, which is obtained by joining the middle points of the top of rectangles of histograms. The extreme values are joined with the x-axis at the half distance of class interval from the variable of the class interval. A graph which is used for understanding the shapes of distributions is known as a frequency polygon. A frequency polygon works as a histogram. It is useful for comparing the sets of data. So, frequency polygon is a graph that is obtained by connecting the middle points of the intervals. We can create a frequency polygon from a histogram also. If the middle top points of the bars of the histogram are joined, a frequency polygon is formed. Frequency polygon and histogram fulfills the same purpose. Graphical display of the frequency table can also be achieved through a frequency polygon. To create a. the intervals are labeled on the X-axis and the Y axis represents the height of a point in the middle of the interval. (2) Page 1 of 7. (b)€€€€ The frequency polygon for the finishing times of non-members is shown below. (i)€€€€€ On the same axes draw the frequency polygon for the finishing times of the members. (2) (ii)€€€€ Seb claims that on average non-members are slower and have more varied finishing times than members.
http://www.math-mate.com/chapter16_10.shtml http://tutorteddy.com/statistics/statistics-frequency-polygons.php http://www.icoachmath.com/math_dictionary/frequency_polygon.html http://onlinestatbook.com/2/graphing_distributions/freq_poly.html http://math.tutorcircle.com/probability-and-statistics/frequency-polygon.html http://tutorteddy.com/statistics/statistics-frequency-polygons.php https://corbettmaths.files.wordpress.com/2012/10/frequency-polygons.pdf
what is shown by a frequency polygon