 Furthermore this theory implies that consumption is smoothed out relative to a person's income which is the reason economists set consumption proportional to potential income rather than actual income.Attempts to test the life-cycle model against real world data have met with mixed success.In a review of the literature, Courant, Gramlich and Laitner (1984) note "but for all its elegance and rationality, the life-cycle model has not tested out very well".