Page 335 - Statistics for Dummies

Chapter 20
Ten Tips for the Statistically
Savvy Sleuth
In This Chapter
▶ Recognizing common statistical mistakes made by researchers and the media
▶ Avoiding mistakes when doing your statistics
his book is not only about understanding the statistics that you come
Tacross in the media and in your workplace; it’s even more about digging
deeper to examine whether those statistics are correct, reasonable, and fair.
You have to be vigilant — and a bit skeptical — to deal with today’s informa-
tion explosion, because many of the statistics you find are wrong or mislead-
ing, either by error or by design. If you don’t critique the information you’re
consuming, in terms of its correctness, completeness, and fairness, who will?
In this chapter, I outline ten tips for detecting common statistical mistakes
made by researchers and by the media and ways to avoid making them
yourself.

Pinpoint Misleading Graphs

Most graphs and charts contain great information that makes a point clearly,
concisely, and fairly. However, many graphs give incorrect, mislabeled, and/or
misleading information; or they simply lack important information that the
reader needs to make critical decisions about what is being presented. Some
of these shortcomings occur by mistake; others are incorporated by design in
hopes you won’t notice. If you’re able to pick out problems with a graph before
you contemplate any conclusions, you won’t be taken in by misleading graphs.

Figure 20-1 shows examples of four important types of data displays: pie
charts, bar graphs, time charts, and histograms. In this section I point out
some of the ways you can be misled if these types of graphs are not made
properly. (For more information on making charts and graphs correctly and
identifying misleading ones, see Chapters 6 and 7.)

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