As this entertaining addition demonstrates, the “how to lie with statistics” genre is alive and well.
Cairo (Chair, Visual Journalism/Univ. of Miami; The Truthful Art: Data, Charts, and Maps for Communication, 2016, etc.) points out that “charts may lie…because they display either the wrong information or too little information. However, a chart can show the right type of information and lie anyway due to poor design or labeling.” In a cheerful introductory chapter, the author explains that, while writing was invented about 5,000 years ago and charts weren’t used until the late 1700s, both are encoded forms of communication with a structure and vocabulary. Readers receive well-researched information about the makeup of a chart along with the warning that this knowledge, like rules of grammar, is necessary but not sufficient. It’s essential to pay attention. Cairo begins with a U.S. map, almost entirely red, that many claim shows the overwhelming popularity of Donald Trump in 2016. But how could that be if he received only 46 percent of the vote? The trick is that the map label shows not voters but counties with Trump majorities. Since large counties (rural) mostly voted for him and small counties (urban) didn’t, such a map is overwhelmingly red. The map, although real, is used to lie. In the generously illustrated chapters that follow, the author delivers a painless, if often uncomfortable education. On a trivial level, one must know what a chart is measuring. A chart of homeless schoolchildren in Florida reveals counties with more than 20 percent. The streets are not full of sleeping students because “homeless” is not defined as “no home” but rather as “lacking a fixed, regular nighttime residence.” There are plenty of no-brainers, sadly widely ignored, such as, “correlation is not causation.” The graph showing that cigarette smoking increases in nations with a greater life expectancy does not prove that smoking is healthy.
An ingenious tool for detecting flaws in charts, which nowadays seem mostly deliberate.