The box-and-whisker plot below the line plot visually shows the important characteristics of a variable's distribution: its mean, median, lower and upper quartiles, and outliers. This plot is scaled according to the X-axis of the histogram.
The left and right edges of the box are located at the sample 25th and 75th percentiles. Thus, the box contains roughly half of the sample values. The vertical line drawn within the box marks the 50th percentile, or median. The plus sign (+) marks the sample mean.
The horizontal lines, or whiskers, extend from the box as far as the data extend, to a distance of at most 1.5 interquartile ranges. Any value more extreme than this is marked with an asterisk (*).