Hey everyone, welcome to this lecture. What is a boxplot. A box plot, also called a box and whisker plot was developed by Professor john tukey of Princeton University. The box plot is a graphical display that simultaneously displays several important features of the data, such as its central tendency, variability, departure from symmetry and identification of observations that lie unusually far from the bulk of the data. The box represents the middle 50% values of the process data. The median is the centerline of the box.

It represents the point for which 50% of data points are above and 50% are below the line. q1 represents the points for which 75% of the data are above and 25% or below the line by q three represents the point for which 25% of the data are above and 75% or below the line. asterisk represents an outlier, and is a point which is more than 1.5 times the interquartile range that is q3 minus q1 in the data. The vertical lines represent a whisker with joins q one or q three with the farthest data point, but other than an outlier. Let's look at this example. There are 12 students in a class most of these students are five to six years old.

You measure the height of each student. You have created a boxplot and it shows the median height is 120.6 centimeter The interquartile range is 0.575 it is calculated by using the formula quartile three minus quartile one or q3 minus q1. Here quartile three is 120 point nine and quartile one is 120 point three to five, no outliers are present. The range is from 120 point one to 120 1.3. That brings us to the end of this lecture. In the next lecture, you will learn how to draw this boxplot on Minitab