Market Share Overestimation and the Noncomplementarity Effect

Recent research indicates that people tend to overestimate the likelihood of an alternative, particularly when an alternative is considered in isolation rather than as part of a set of alternatives. The present experiment shows that subjective market share overestimation and noncomplementary market share estimates are more likely to be observed for individuals who are high (vs. low) in concern about cognitive closure or when a small (vs. large) set of alternatives is considered. Implications of the results for understanding managerial decision making are discussed.