Five number summary
The five numbers are the maximum, the minimum, the median and the upper and lower quartiles. This set of numbers can tell you about the central tendency of your data, the spread, the extreme values, and provide low order information about the shape of the distribution. The blood pressure data sets came from Dr Bradstreet’s Favorite Datasets in Early and Late phases in Drug Research.
Box and whisker plot next, so I can explain how to interpret the five number summary. This series is part of a few sessions I’m planning for some degree students. The box and whisker illustration here was produced using the Gnumeric spreadsheet – it has a useful selection of statistical graphs and can export graphs as SVG or in a variety of bitmaps. Version 1.9.9 is in the Ubuntu 9.10 repositories.