Decision Making under Uncertainty: An Experimental Study in Market Settings

Research Report

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Insights Report

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When making financial decisions under uncertain conditions, do people actually behave as widely used theories predict?

Summary

Subjective expected utility theory, or SEU, is the workhorse model of decision making under uncertainty, and economists assume routinely that agents behave according to its precepts. This study evaluates SEU’s empirical validity in experimental settings in which subjects were asked to make decisions resembling portfolio allocations. The study design allowed the researchers to quantify how far each individual subject’s choices were from what the theory would suggest, compare results across subject populations, and gauge the relationship between subjects’ choices and sociodemographic characteristics.

Key Insights

The vast majority of subjects do not conform with SEU theory.
Subjects exhibit similar responses to uncertainty generated by simulated low- and high-volatility stock prices.
The degree of compliance with the theory is very similar for undergraduate students, younger adults (20-39), middle-aged adults (40-59) and older subjects (60 or older).
Subjects with a high degree of financial literacy behave significantly closer to the theory, based on one of two financial literacy measures tested; but there is no significant relation with the second measure.
Subjects with more education are significantly closer to theory than less-educated subjects.

Subjects on average exhibited basic levels of rationality by responding to changes in asset prices as SEU would predict, but not to an extent fully consistent with the theory.

Methodology

The researchers conducted two studies with similar structures involving two different populations: undergraduate students in the laboratory, and a representative sample of the U.S. population drawn from a large-scale panel. In addition to studying SEU, the researchers considered max-min expected utility (MEU), the most commonly used alternative to SEU. They found MEU has no additional explanatory power.