Unveiling Statistical Deception

There are three kinds of lies: lies, damned lies, and statistics. Benjamin Disraeli (1804 - 1881)

Misleading Scale Taken from Triola, Essentials of Statistics. Addison Wesley.

Misleading Scale http://www.mworld.com/m/ir/stockchart.asp

Missing Numbers

Pictographs Double the length, width, and height of a cube, and the volume increases by a factor of eight Taken from Triola, Essentials of Statistics. Addison Wesley.

Pictographs

In 1936 Literary Digest magazine sent more than 10 million ballots to readers to get their preferences in the upcoming presidential election between Franklin D. Roosevelt and Alfred M. Landon. The returns indicated that Landon, the Republican nominee, would win handily. Roosevelt won in the first great landslide election of the 20th century. He carried all states except Maine and Vermont. Choice of Sample http://www.britannica.com/ebi/article-9276570?&query=newspapers&ct=%22ebi%22

Choice of Sample In an ABC Nightline poll, 186,000 viewers each paid 50 cents to call a “900” telephone number with their opinion about keeping the United Nations in the United States. The results showed that 67% of those who called were in favor of moving the United Nations out of the United States. Taken from Triola, Essentials of Statistics. Addison Wesley.

Choice of Sample The Hawaii State Senate held hearings when it was considering a law requiring that motorcyclists wear helmets. Some motorcyclists testified that they had been in crashes in which helmets would not have been helpful. Which important group was unable to testify? Taken from Triola, Essentials of Statistics. Addison Wesley.

Choice of SamplePossibility of Lying • “Have you ever used illegal drugs?" • “Do you favor a constitutional admendment that would outlaw most abortions?" • “Have you had more than one sexual partner in the past 6 months?" • “Have you ever driven a motor vehicle while intoxicated?" http://www.dartmouth.edu/%7Echance/teaching_aids/RResponse/RResponse.html

Question Phrasing 97% yes: “Should the President have the line item veto to eliminate waste?” 57% yes: “Should the President have the line item veto, or not?” Taken from Triola, Essentials of Statistics. Addison Wesley.

Question Phrasing Would you say that traffic contributes more or less to air pollution than industry? 45% blamed traffic, 27% blamed industry Would you say that industry contributes more or less to air pollution than traffic? 24% blamed traffic, 57% blamed industry Taken from Triola, Essentials of Statistics. Addison Wesley.

Question Phrasing • “Welfare” vs. “Care for the poor” • “Pro-abortion” vs. “pro-choice” • Others?

Correlation vs. Causation A study showed that truck drivers weigh more than adults who do not drive trucks. Conclusion: Trucks cause people to gain weight. Taken from Triola, Essentials of Statistics. Addison Wesley.

The number of people per television in a country is negatively correlated with the average life expectancy. Can we conclude that one causes the other? http://www.amstat.org/publications/jse/v2n2/datasets.rossman.html

Ice cream sales and number of drownings are correlated. Does this mean that eating ice cream causes drowning? Or that people eat more ice cream after someone drowns? Taken from Against all Odds. Video on Demand from Annenberg.

As reported by CNN and USA Today, the poll found … fewer than one in five – 18 percent – in six of the nine countries believe Arabs carried out the September 11 terrorist attacks. (Three countries wouldn't let Gallup polltakers ask the question.) You won't find those results on Gallup's Web site, however. That's because of one rather big problem: These eye-opening results were "actually the average for the countries surveyed regardless of the size of their populations," the NCPP noted. "Kuwait, with less than 2 million Muslims, was treated the same as Indonesia, which has over 200 million Muslims." Mistakes By Richard Morin and Claudia Deane Washington Post Staff WritersFriday, March 22, 2002

Unveiling Statistical Deception