Six Sigma – Box Plots

Box Plots are used for multiple purposes and few of them are below

• To Visualize Mean and Variation
• To compare the same metric across the locations, applications, engineers etc.
• To Identify the outliers in case any
• To compare the distributions

Box Plots are sometimes referred as Box and Whisker plots. These types of graphs are used to display the range, median and quartiles. When they are completed, a box contains the first and third quartiles. Whiskers extend from the box to the minimum and maximum values of the data.

There are several steps in constructing a box plot. The first relies on the 25^th, 50^th, and 75^th percentiles in the distribution of scores. The 50^th percentile is drawn inside the box. Therefore, the bottom of each box is the 25th percentile, the top is the 75^th percentile, and the line in the middle is the 50^th percentile.

How to read the box plots:

• Median is indicated by the vertical line that runs down the center of the box
• Display two common measures of the variability or spread in a data set
• Range, Interquartile Range
• Shape of the data