Speaking on Data’s Behalf: What Researchers Say and How Audiences Choose

Background

Bayesian statistics have become popular in the social sciences, in part because they are thought to present more useful information than traditional frequentist statistics. Unfortunately, little is known about whether or how interpretations of frequentist and Bayesian results differ.

Objectives

We test whether presenting Bayesian or frequentist results based on the same underlying data influences the decisions people made.

Research Design

Participants were randomly assigned to read Bayesian and frequentist interpretations of hypothetical evaluations of new education technologies of various degrees of uncertainty, ranging from posterior probabilities of 99.8% to 52.9%, which have equivalent frequentist p values of .001 and .65, respectively.

Subjects

Across three studies, 933 U.S. adults were recruited from Amazon Mechanical Turk.

Measures

The primary outcome was the proportion of participants who recommended adopting the new technology. We also measured respondents’ certainty in their choice and (in Study 3) how easy it was to understand the results.

Results

When presented with Bayesian results, participants were more likely to recommend switching to the new technology. This finding held across all degrees of uncertainty, but especially when the frequentist results reported a p value >.05. Those who recommended change based on Bayesian results were more certain about their choice. All respondents reported that the Bayesian display was easier to understand.

Conclusions

Presenting the same data in either frequentist or Bayesian terms can influence the decisions that people make. This finding highlights the importance of understanding the impact of the statistical results on how audiences interpret evaluation results.