Skeptic’s Café: Understanding Popular Uses of Percentages

Skeptic’s Café: Understanding Popular Uses of Percentages

Pacific Standard

Peter M. Nardi, Professor Emeritus of Sociology
Pitzer College, Claremont, California

Four New Jersey women in March accused the Campbell Soup Company of misleading customers with claims of lower sodium levels in its “25% Less Sodium Tomato Soup.” Whether the soup has more or less sodium than regular versions is not for me to investigate. I want to focus on the “25% less” phrase — a type of claim we see regularly in ads and new product labels — and in the process provide some numerical literacy skills to our arsenal of skeptical thinking tools.

In an age when quantitative thinking is at a premium and “innumeracy,” as cognitive scientist Douglas R. Hofstadter termed it, is a problem, many people easily misinterpret numbers and become wary about statistics. Sometimes this skepticism is for good reason – remember that oft-cited phrase “there are three kinds of lies: lies, damned lies and statistics.”

But turning our backs on numbers is a mistake. We require critical thinking skills to make sense of data that appear in commercials, politician-mediated public opinion polls, official documents and research studies…

Consider this paragraph from a New York Times article about the increase in multiracial people in the latest 2010 U.S. Census: “In North Carolina, the mixed-race population doubled. In Georgia, it expanded by more than 80 percent, and by nearly as much in Kentucky and Tennessee. In Indiana, Iowa and South Dakota, the multiracial population increased by about 70 percent.” A few paragraphs later the article reports a possible national multiracial growth rate of 35 percent, maybe even a 50 percent increase from the last census in 2000 when 2.4 percent of Americans selected more than one race.

With these numbers coming at you fast and furious, it takes a moment to reflect on what is actually being said and what information is missing…

…Going back to the Census figures quoted in The New York Times, it’s one thing to claim that the multiracial population may increase 50 percent, but when the original figure is only 2.4 percent of Americans, a 50 percent increase simply means that the 2010 multiracial population could end up around 3.6 percent of the population. The number 50 surely sounds more impressive than the smaller 3.6 figure. Manipulating these numbers can create misleading impressions, sometimes done with intention…

Read the entire article here.

Tags: , ,