Chapter 3

Visual Displays of Data

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How to Lie with Visual Statistics

  • “The Most Misleading Graph Ever Published”
  • Techniques for Misleading with Graphs

Common Types of Graphs

  • Scatterplots
  • Line Graphs
  • Bar Graphs
  • Pictorial Graphs
  • Pie Charts

How to Build a Graph

  • Choosing the Appropriate Type of Graph
  • How to Read a Graph
  • Guidelines for Creating a Graph
  • The Future of Graphs

Next Steps: Multivariable Graphs

BEFORE YOU GO ON

  • You should understand the different types of variables—nominal, ordinal, and scale (Chapter 1).
  • You should understand the difference between independent variables and dependent variables (Chapter 1).
  • You should know how to construct a histogram (Chapter 2).

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Figure 3-1

Graphs That Persuade Florence Nightingale’s coxcomb graphs, “Causes of Mortality in the Army in the East,” address the period from April 1854 to March 1856. This adaptation of her April 1854 to March 1855 graphic is called a coxcomb graph because the data arrangement resembles the shape of a rooster’s head. The 12 sections represent the ordinal variable of a year broken into 12 months. The size of the sections representing each month indicates the variable of how many people died in that particular month. The colors correspond to the different causes of death.

The legendary nineteenth-century nurse Florence Nightingale was also known as the “passionate statistician” (Diamond & Stone, 1981). The lens of time has softened the image of this sarcastic, sharp-elbowed infighter (Gill, 2005) who created trouble simply by counting things. She counted supplies in a closet and discovered corruption; she counted physicians’ diagnoses and discovered incompetence. She created the visual display in Figure 3-1 after counting the causes of death of British soldiers in the Crimea. The British army was killing through poor hygiene more of its own soldiers than were dying due to wounds of war—and an outraged public demanded change. That is one powerful graph!

This chapter shows you how to create graphs, called figures in APA-speak, that tell data stories. We recommend Displaying Your Findings by Adelheid Nicol and Penny Pexman (2010) for a more detailed look, but a checklist at the end of this chapter will answer most of your questions about how to create graphs.