Lukas Meub and Till Proeger, “Are Groups 'Less Behavioral'? The Case of Anchoring,” February 18, 2014; updated version available here.
• Do groups (as opposed to individuals) filter out irrationality and promote rationality? Do they “debias”? The broad consensus position is “yes,” though perhaps the advantage of a group is more pronounced with issues that have objectively correct answers (as opposed to being matters of judgment.)
• Experiments conducted by Meub and Proeger used groups of three players, faced with 15 questions, 5 each from the categories of: factual knowledge; likelihoods; and, price estimation. The experiments involved two conditions, the “calibration” condition and the “anchor” condition.
• The calibration condition is employed to identify appropriate anchors. The high anchor and low anchor values come from the 15th and 85th percentiles of unanchored responses. There is a small monetary incentive to guess well; payments varied (based on performance and condition) from 5 to 15 euro.
• The anchor index summarizes how much the anchors sway responses. The numerator of the index is the median difference in responses between the high anchor group and the low anchor group. The denominator is the difference between the high and low anchor values themselves. An anchor index of zero indicates that people gave the same response, on average, no matter what anchor they were exposed to. An anchor index of one indicates that the respondents, on average, just let the anchor be their response.
• The authors find that over all 15 questions, groups are less biased, with an anchor index of .34 as opposed to .52 for individuals.
• High anchors seem to matter more, but in any event, groups are less biased than individuals on the factual knowledge questions. Groups showed no advantage over individuals on the probability questions, nor for price estimation.
• Participants were asked if they perceived an anchoring problem, and the responses did not vary between individuals or groups.
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