Decision Sciences Volume 32 Number 2 Spring 2001 Printed in the U.S.A. The Effectiveness of Decisional Guidance: An Empirical Evaluation Mihir Parikh Institutefor Technologyand Enterprise, Polytechnic University, Five Metrotech CenteT LC401, Brooklyn, hT 11201, e-mail: mparikh@poly.edu Bijan Fazlollahi Computer Information System, J. Mack Robinson College of Business Administration, Georgia State University,Atlanta GA 30303, e-mail: bijan@gsu.edu Sameer Verma Information Systems and Business Analysis, College of Business, San Francisco State University, 1600 Holloway Ave., San Francisco, CA 94132, e-mail:sverma@sfsu.edu ABSTRACT Decisional guidance is defined as how a decision support system (DSS) influences its users as they structure and execute the decision-making process. It is assumed that deci- sional guidance has profound effects on decision making, but these effects are under- studied and empirically unproven. This paper describes an empirical, laboratory- experiment-based evaluation of the effectivenessof deliberate decisional guidance and its four types. We developed and used a comprehensivemodel consistingof four evalu- ation criteria: decisionquality,user satisfaction,user learning,and decision-making effi- ciency. On these criteria, we compared decisional guidance versus no guidance, informative versus suggestivedecisionalguidance,and predefined versus dynamic deci- sional guidance. We found that deliberate decisionalguidance was more effective on all four criteria; suggestiveguidance was more effective in improving decision quality and user satisfaction,and informativeguidance was more effective in user learningabout the problem domain, whereas dynamic guidance was more effective than predefined guid- ance in improving decision quality and user learning; and both suggestiveguidance and dynamic guidance reduced the decision time. Subject Areas: Decision Support Systems, Decisional Guidance, DSS Eflective- ness, Experimental Design, and Laboratory Experiment. INTRODUCTION A major difference between decision support systems (DSS) and other information systems is that DSS emphasize decision-making effectiveness and decision-mak- ing efficiency rather than the efficiency alone (Keen & Scott Morton, 1978; Evans & Riha, 1989). Decision-making effectiveness means appropriately identifying what should be done in a decision-making situation and ensuring that the chosen 303