This example illustrates an extremely rewarding method of collaboration between psycho-sociological specialists and econometric specialists. Such collaboration should be developed more end more in the study of many forecasting problems. In this connection, the rule to be followed in approaching the problems appears to be the following: where statistics are available (trade statistics, company sales, or the results of consumer research, for example), it seems advisable to make a preliminary statistical and econometric analysis which comes up with significant results, warns about some peculiarities, and suggests some explanations. This is where the psychologist comes in on already cleared ground where he may better center" his work. Lastly, collaboration between the two approaches should occur to establish a synthesis of the results. On the other hand, where there are practically no statistics, they must be reconstituted by investigation. However, before undertaking it, is extremely useful for the psychologist to make a preliminarily exploratory study of the problems, whereby he can establish the fundamental hypotheses. Then an extensive investigation may be perfected which permits the psychologist to verify his hypotheses, and supplies econometric specialist the quantified elements which he needs.