Box & Whisker plot helps you study the distribution of your data. To create the Box plot you need 0 or more dimensions and 1 or more measure.
Once you drag required dimensions and measures, click on Box & Whisker plot from ‘show me’ section. Your graph will get converted into a Box plot which will look something like this.
The Box plot gives you few horizontal lines, 2 colors and 1 vertical line. Let’s understand how to read this graph. In Tableau if you hover on the Box plot, it will give 5 details.
1. Median: If you sort all the numbers in ascending order then Median is the central value from your data. Median is used for finding the central tendency of your data.
2. Upper Quartile & lower Quartile: Quartile is dividing something in 4 sections. Box plot will divide the complete graph in 4 sections so you can clearly see your data distribution.
3. Upper Whisker & Lower Whisker: Whisker will include all the points from your data except outliers. To plot whisker, we have 2 options.
a. Maximum extent of the data
b. 1.5 times the IQR (Inter-Quartile Range)
Any point which is out of Whisker will be considered as Outlier. If you want to change the whisker plot options then you can
Right click on the number axis → Click on Edit Reference Line → Select Plot Whisker options