how to make a random box and whisker plot

Question

Just details on how to make a box and whisker plot.

Answer 1

Box and whisker plot's can be a bit complicated depending on how detailed you want them to be. For every Box and whisker plot though there are at least 5 elements. The minimum value of data, the maximum value, the median and the first and third quartile's. The "box" part starts at the first quartile and extends all the way to the third quartile.

The first quartile can be found by taking the half of the data points that are less than or equal to the median and finding the median of that smaller list of data points. The third quartile can be found by taking the half of the data points that are greater than or equal to the median and finding the median of THAT smaller list of data points.

Please note that this is ONE way to find the first and third quartiles. There is a more complicated and more "accurate" way to find them which you can do by finding the 25th percentile of the data for the first quartile and the 75th percentile of the data for the third, but if your teacher hasn't mentioned anything about percentile's or equations for finding percentiles then do not worry about it.

Anyway so you draw a box from the first quartile extending to the third and you draw a horizontal line inside the box that represents the median.

Next is the whiskers. Again there are multiple ways to calculate the whiskers some of which are more involved than others. The easiest way is simply to extend a line from the edge of your box to the minimum or maximum value in your data set depending on which end of the box you are drawing the line from (from the 3rd quartile you would draw to the maximum value, and from the 1st you would draw to the minimum value). Some teachers might only have you draw whiskers to the upper adjacent or the lower adjacent, but again if those words don't mean anything to you then don't worry about it. It's easiest to just draw it to the maximum and minimum.

So to recap you have a total of 5 lines drawn at the following locations:

minimum

first quartile

median

third quartile

maximum

There is a line like a whisker connecting the first quartile to the minimum and the third quartile to the maximum, and a box around the first, and third quartile and the median (also called the second quartile).

Some box plot's are more in depth but ultimately depict the same exact thing.

Hope that helps! Let me know if you have any questions.