This chapter describes two kinds of procedures for depicting and summarizing data: frequency distributions and graphs. The procedures for constructing frequency distributions for quantitative variables differ slightly from those used to construct frequency distributions for qualitative variables. Also, different kinds of graphs are used to depict the two kinds of variables. The chapter ends with a description of some commonly encountered distributions and some ways that graphs can mislead you.
After reading the chapter, you should know the following:
■ How to construct frequency distributions for quantitative and qualitative variables
■
The merits of relative frequency distributions and cumulative frequency distributions
■ How to construct bar graphs and pie charts for qualitative variables
■ How to construct histograms, frequency polygons, cumulative polygons, and stem-and-leaf displays for quantitative variables
■
The names of commonly encountered distributions and four important properties of distributions
■ How you can be mislead by graphs