SMABS 2004 Jena University
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European Association of Methodology

Department of methodology and evaluation research

Jena University

Contributions: Abstract

Characterisation of individual opinion change in decision making groups

Anthony Stacey Mike Bendixen
Wits Business School
South Africa

A model of decision making groups has been developed that incorporates the power and influence profile of each group member, plus the nature and extent of influence of effects or events external to the group.

The model can represent a variety of behaviours of group members, including polarisation, depolarisation, groupthink, consensus, vacillation, and the formation of cliques. The model is used to demonstrate that the opinions of group members are time dependent, and the critical feature in determining the behaviour of the group is a matrix of association among the group members, and its related eigenvalues.

In particular, it can be shown that eigenvalues with moduli less than unity characterise groups comprised of members with stable preferences, eigenvalues with a modulus approximately equal to unity characterise chaotic preference shifts, and at least one eigenvalue with a modulus greater than unity characterise diverging preferences. It can also be shown that real eigenvalues are indicative of enduring preference shift, whereas vacillation occurs when there are complex eigenvalues. In general the principal components of the preferences of the group members stabilise over time, although the factor loadings and factor scores may exhibit orbital trajectories when eigenvalues are complex.

The model indicates that pure consensus is not necessarily the result of recurring interaction among group members. The model suggests that (a) reducing the degree of influence of group members and (b) exposing the group to external influences will militate against polarisation and chaotic behaviour. Moreover, the final opinions of the group members depend wholly on the process and not on their initial tendencies.