Judging a Part by the Size of Its Whole: The Category Size Bias in Probability Judgments

Abstract

Consumers might be said to have a prediction addiction—they speculate about sports, politics, weather, stocks, sweepstakes, health, and relationships, to name just a few areas. What’s more, predictions often guide their decisions.For example, they may decide to carry an umbrella after considering the chance of rain, to invest after forecasting the stock market’s performance, or to marry after predicting the likelihood of marital bliss. With all this practice, one might expect consumers to be good at judging probability. However, their predictions are often wrong.