Thinking in Bets: Making Smarter Decisions When You Don't Have All the Facts

by Annie Duke

He and several colleagues looked at whether conclusions from objective data were driven by subjective pre-existing beliefs on a topic. When subjects were asked to analyze complex data on an experimental skin treatment (a “neutral” topic), their ability to interpret the data and reach a conclusion depended, as expected, on their numeracy (mathematical aptitude) rather than their opinions on skin cream (since they really had no opinions on the topic). More numerate subjects did a better job at figuring out whether the data showed that the skin treatment increased or decreased the incidence of rashes. (The data were made up, and for half the subjects, the results were reversed, so the correct or incorrect answer depended on using the data, not the actual effectiveness of a particular skin treatment.) When the researchers kept the data the same but substituted “concealed-weapons bans” for “skin treatment” and “crime” for “rashes,” now the subjects’ opinions on those topics drove how subjects analyzed the exact same data. Subjects who identified as “Democrat” or “liberal” interpreted the data in a way supporting their political belief (gun control reduces crime). The “Republican” or “conservative” subjects interpreted the same data to support their opposing belief (gun control increases crime).