Lessons from the debate on Cole's model closure**Note of the Editor†in†Chief: While the preparations for this issue were in progress, the regional science community was struck by the information that Moss Madden fell seriously ill shortly after his return from South Africa, where he participated in an RSAI symposium. Only a few days later, everybody was shocked by the announcement of his sudden untimely death at the age of 53. Professor Moss Madden was an internationally renowned scholar and highly appreciated colleague. His academic legacy comprises numerous seminal contributions to input–output analysis, simulation modeling, and forecasting in regional science. Moss was a good friend of many of us active in regional science, and will be missed. We offer our sincere condolences to his family, friends, and colleagues. As a tribute, commemorating his relentless efforts to advance our knowledge of regional input–output analysis, we dedicate this article to him. It reflects on the debate to which Moss contributed so much

Cole (1989, 1997, 1999) advocates the introduction of expenditure lags and the fullest possible closure of single†region input†output models. Jackson et al. (1997, 1999) claim that closing also with regard to the Rest†of†the†World leads to inconsistencies and zero exogenous demand, which makes impact studies impossible. Using somewhat different arguments I agree with them: endogenous interregional feedbacks are conceptually impossible outside a full interregional model. Two hardly discussed points, however, remain for further research. First, closing with regard to all other regional demand is precarious too, as it empirically and theoretically amplifies the one†sidedness of the demand†driven input†output model. Realistic impact studies ask for models including supply†side aspects. Second, adding expenditure lags is an improvement, but the way in which this can be done and should be done requires further theoretical development.