This article reports results of a quantitative analysis of I. L. Janis
's (1982) original specification of the groupthink model. The study bu
ilds on the earlier work on 19 cold war crises conducted by Herek, Jan
is, and Huth (1987), who found that information-processing errors in g
roup decision making were directly related to unfavorable outcomes. Th
e present research looks further back in Janis's casual story to inves
tigate the factors that give rise to the information-processing errors
. This data identify five key antecedent conditions: lack of tradition
of impartial leadership, lack of tradition of methodical procedures,
overestimation of the group, closed-mindedness, and pressures toward u
niformity Several factors that Janis anticipated as important antecede
nt conditions do not correlate with faulty decision making, such as gr
oup homogeneity and a recent failure. The results indicate that faulty
decision making has its roots in leadership style, traditional group
procedures, and patterns of group behavior.