II. Graphing Distributions
Prerequisites
none
 Introduction
 Qualitative
Variables
 Quantitative
Variables
 Stem and Leaf Displays
 Histograms
 Frequency Polygons
 Box Plots
 Box Plot Demonstration
 Bar Charts
 Line Graphs
 Exercises
Graphing data is the first and often most important step in
data analysis. In this day of computers, researchers all too often
see only the results of complex computer analyses without ever
taking a close look at the data themselves. This is all the more
unfortunate because computers can create many types of graphs
quickly and easily.
The introductory
section of this chapter gives
an example in which a wellconstruted graph makes it clear that
there was a bias in the draft lottery of 1969. The two following
sections discuss common graphs for qualitative and quantitative variables.
