In this session, we examined several different ways to organize continuous data measured on a number line. It is often helpful to organize this kind of data by grouping it. The stem and leaf plot is a grouping device that is useful for moderately sized data sets.
The grouped relative frequency table and histogram are more useful devices for larger data sets, since they allow you to visualize your data as portions of larger intervals. These representations, along with grouped cumulative frequency and relative frequency tables, allow you to recognize trends in large data sets by comparing the relative number of data values in each interval.
The following Interactive Activity uses the hat-size data from Part D to allow you to review these tabular and graphic representations of your data. Click through each representation to see how the display in one format relates to the display in the other format.
This activity requires the Flash plug-in, which you can download for free from Macromedia's Web site.
All of these methods are useful for summarizing the variation in numeric data so that we can provide better answers to the statistical questions we're investigating.