MARGINAL PROPENSITY TO INVEST: The proportion of each additional dollar of national income that is used for investment expenditures. Or alternatively, this is the change in investment expenditures due to a change in national income. Abbreviated MPI, the marginal propensity to invest is the slope of the investment line used in the analysis of Keynesian economics. As such, it also plays a role in the slope of the aggregate expenditure line and the multiplier effect. See also | investment expenditures | national income | investment line | Keynesian economics | multiplier | aggregate expenditures line | marginal propensity to consume | marginal propensity to save | marginal propensity to import | marginal propensity for government purchases |
