Weighting and Trimming: Heuristics for Aggregating Judgments under Uncertainty

Ilan Yaniv

In making major decisions (e.g., about medical treatment, acceptance of manuscripts for publication, or investment), decision makers frequently poll the opinions and subjective estimates of other judges. The aggregation of these opinions is often beset by difficulties. First, decision makers often encounter conflicting subjective estimates. Second, estimates are often expressed with a measure of uncertainty. The decision maker thus needs to reconcile inconsistencies among judgmental estimates and determine their influence on the overall aggregate judgement. In the empirical studies, I examine the idea that weighting and trimming are two important heuristics in the aggregation of opinions under uncertainty. The results from these studies are contrasted with the findings of a normative study using a computer simulation that was designed to assess the objective effects of weighting and trimming operations on the accuracy of estimation.

April, 1997
Published in: 
Organizational Behavior and Human Decision Processes 69 (1997), 237-249