V. THE SHORT PERIOD AND THE LONG PERIOD
So far we have examined quite a number of ways in which the simple Keynesian model must be modified in order to define the take of fiscal policy, given the single objective of maintaining full employment with out inflation. As yet, the model in all its variants deals only with the short run, during which period of time the labour force is constant in size, and changes in the capital stock reflected in alterations in I affect only the level of money national income and not the level of (potential) national output.