Whiskers extend from the quartiles to the farthest observation not farther than 1.5 times the distance between the quartiles (the interquartile range). Beyond the whiskers, extreme observations are ...

Learn how to calculate the interquartile range from a variety of different data types and draw and interpret box-and-whisker diagrams.

The box plot is based on sample statistics, which are estimates of the corresponding population values. Sample variability will be reflected in the variation of all aspects of the box plot (Fig. 2).

The interquartile range shows the range in values of the central 50% of the data. To find the interquartile range, subtract the value of the lower quartile Q1 from the value of the upper quartile Q3.