Psychology prof on how Trump uses statistics to mislead

Paul Slovic

President Donald Trump recently tweeted a statistic stating that “nearly 3 in 4 individuals convicted of terrorism-related charges are foreign-born.” It was taken from a report by the departments of justice and homeland security.

However, according to UO psychology professor Paul Slovic, using that statistic to imply that excluding the foreign-born would decrease terrorist attacks is a misleading, psychologically tricky tactic.

Slovic and Leaf Van Boven, a psychology professor at the University of Colorado, co-wrote an article on the topic for Politico.

“The 75 percent statistic ignores the rarity of terrorist-related activities despite the very large number of foreign-born individuals in the United States,” Slovic and Van Boven write. “Treating 75 percent as a meaningful measure of risk is deceitful — it’s lying with statistics.”

Close to 75 percent of NBA players are African-American, but less than 0.01 percent of African-American men are NBA players. Especially when responding to risk, people often treat these two types of statements as equally valid.

This is known as an inverse fallacy. Despite the 75 percent statistic, you can be highly confident that a random African-American man is not an NBA player.

“Similarly, we can be confident that an individual convicted of terrorism-related charges in a U.S. federal court is foreign-born (a probability of about 75 percent),” Slovic and Van Boven write. “But if an individual is foreign-born, the likelihood that the person has engaged in terrorism-related activities is nearly zero.”

For the full story, see “The Psychological Trick Behind Trump’s Misleading Terror Statistics”.

Slovic is the president of Decision Research and a professor of psychology at the UO. He studies judgment and decision making, especially under conditions of risk. His most recent research examines psychological factors contributing to apathy toward genocide.