“…Although conventional econometric studies tend to reject the model of notional demand in favor of the model of effective demand including the output constraint ( [12] or [34]), they conclude, nevertheless, with the combined influence of output and profits, whether the latter affects the level ( [II], [23], [27]), or the speed of realization of desired investment ( [3], [8], [12], [16], [26], [30]). These models, which can be justified, for example, by the aggregating of firms faced with different situations, do not, however, make it possible to distinguish the influence of the various constraints at different periods.…”