Accession Number:

ADA568559

Title:

The Probabilities of Unique Events

Descriptive Note:

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON DC

Report Date:

2012-08-30

Pagination or Media Count:

35.0

Abstract:

Many theorists argue that the probabilities of unique events, even real possibilities such as President Obamas re-election, are meaningless. As a consequence, psychologists have seldom investigated them. We propose a new theory implemented in a computer program in which such estimates depend on an intuitive non-numerical system capable only of simple procedures, and a deliberative system that maps intuitions into numbers. The theory predicts that estimates of the probabilities of conjunctions should often tend to split the difference between the probabilities of the two conjuncts. We report two experiments showing that individuals commit such violations of the probability calculus and corroborating other predictions of the theory, e.g., individuals err in the same way even when they make non-numerical verbal estimates, such as that an event is highly improbable.

Subject Categories:

  • Statistics and Probability

Distribution Statement:

APPROVED FOR PUBLIC RELEASE