A credibility model of policy decision making: Effects of computer media, advocacy, and policy arguments

Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Public Administration



Subject Categories

Public Administration


This research investigates the use of heuristics by decision makers to assess the believability of policy analysis information. The model proceeds from the assumption that decision makers operate in a complex decision environment with limited time, information, and cognitive resources. Drawing upon the work of Toulmin and Bozeman, this model explains how decision makers integrate and weigh various types of evidence in order to make a credibility assessment. The principal objective of this research is to understand the circumstances under which a decision maker will trust in a policy analysis product. Research from the communications, decision making, and evaluation literatures is integrated into a communications model which organizes the determinants of policy decision making. Hypotheses derived from this model are then tested through a controlled experimental study. Subjects include public policy students as well as practicing public administrators. Through the use of an unstructured decision problem, the relative influence of media and various arguments on credibility is revealed. Individual decision makers are asked to make a decision on a telecommunications policy problem. The subjects are exposed to an executive summary of the results of contracted policy analysis as well as a number of comments on the contracted policy analysis. This second set of comments operationalizes the various credibility heuristics that could be utilized by policy decision makers. The study found that decision makers could not be classified into those decision makers who rely on expertise and those who rely on their own analysis to assess the believability of policy information. While arguments about the quality of data affected the perceived difficulty of the decision, these arguments did not affect the credibility of policy analysis. Arguments about logical consistency did not affect the perceived difficulty of the decision but were shown to have a strong effect on the credibility of policy analysis. The perception of logical consistency was also important to whether decision makers utilized theoretical information. Of those decision makers who received their information through a computer, experienced computer users rated the information as less credible than inexperienced users. The implications from these and related findings for policy analysis are then discussed. (Abstract shortened with permission of author.)


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