Aggregation Bias

Abstract

We propose an axiomatic approach to a decision maker’s information aggregation problem. This axiomatic analysis provides a positive model of the decision maker’s evidence assessment process, wherein submitted credible evidence is aggregated into an overall assessment that is responsive to the individual assessments provided. We show that the axiomatic approach produces a two-parameter family of functions and the parameters of the aggregation function have natural interpretations as the decision maker’s bias against the information provider’s report and the breadth of the interpretation of the decision maker’s perspective. We consider two different applications and provide empirical evidence that the decision makers use this form of information aggregation in practice.