What is a Box and Whisker Plot (or Boxplot) graph?
A box and whisker plot is a way of summarizing a set of data measured on an interval scale. It is often used in exploratory data analysis to show the shape of the distribution, its central value, and variability. The picture produced consists of the most extreme values in the data set (maximum and minimum values at the ends of the line), the lower and upper quartiles (edges of the box), and the median (line through the box). (NOTE: The lines extending from the box may be adjusted to represent a certain fraction of the data: they could be set at 5% and 95% or they could represent the minimum and maximum values.) A box plot, as it is often called, is especially helpful for indicating whether a distribution is skewed and whether there are any unusual observations (outliers) in the data set. Box and whisker plots are also very useful when large numbers of observations are involved and when two or more data sets are being compared. 25% Lower Quartile 50% Median 75% Upper Quartile 20. What i
