ABSTRACT
This chapter deals with the representation of data sets in charts or graphs. l In a bar chart only discrete categories of data are presented for comparison and this must
be done fairly, without visual distortion. l Line charts are useful for demonstrating a time series – changes over time in a measure of
a person or group. l Interval data points, grouped into categories, can be represented graphically as a histogram
or as a frequency polygon. l Tukey (1977) promoted techniques of exploratory data analysis with an emphasis on
thorough examination of patterns before submitting data sets to tests of statistical significance. Two methods are included here: stem and leaf diagrams, and box-plots.
