Evidence-Based Software Engineering

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Glossary - box plot

Indexbox plot

A box plot is a means of showing the way that data values are distributed, in particular, of demonstrating any skew in the distribution in a visual manner. The core 'box' has a line for the median value, and the upper and lower bounds of the box are the upper quartile and lower quartile values respectively, where these are the data values with index position half way between the median and the upper and lower values of the dataset. The 'whiskers' on the 'tails' are determined by multiplying the box length by 1.5 and adding/subtracting the values of the upper/lower fourths respectively (and then truncating to the nearest actual value in the dataset). Any values lying outside of these are plotted as separate 'outliers'.

This entry was last updated on 5 August 2008