Group model building effectiveness: a review of assessment studies<FNR></FNR><FN>The authors gratefully acknowledge David Lane's useful comments on a previous version of this paper as well as the valuable suggestions made by the anonymous reviewers. </FN>

Over the last decades system dynamicists have experimented with approaches to achieve more involvement of their clients in the model building process. As a result the number of reports in the literature on the use of system dynamics as an organizational intervention tool has increased dramatically. From the literature we have identified 107 cases that provide details on the modeling process and the assessment of results. The cases show a wide variety in the way the interventions are reported and assessed. From a research point of view this is clearly an undesirable state of affairs. This article reports on a meta analysis of findings of these studies and tries to provide an overview of outcome studies on system dynamics interventions. It attempts to draw some preliminary conclusions on the effectiveness of system dynamics modeling interventions, to clarify differences in definitions of outcomes, and to provide guidelines for more standardized assessments and reports. Rather than remaining in the stage of single case descriptions, the latter will enable the accumulation of research results in the future, a prerequisite for institutional learning within the system dynamics community. Copyright © 2002 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]