Congratulations. You've been appointed economic adviser to...

Congratulations. You've been appointed economic adviser to Happyland. Your research assistant says the country's mpe is .8 and autonomous expenditures have just risen by $$\$ 20$$. a. What will happen to income? b. Your research assistant comes in and says he's sorry but the mpe wasn't .8; it was .5. How does your answer change? c. He runs in again and says exports have fallen by $$\$ 10$$ and investment has risen by $$\$ 10$$. How does your answer change? d. You now have to present your analysis to the president, who wants to see it all graphically. Naturally you oblige. $\mathrm{LO} 2, \mathrm{LO} 3, \mathrm{LO} 4$

Congratulations. You've been appointed economic adviser to Happyland. Your research assistant says the country's mpe is .8 and autonomous expenditures have just risen by $$\$ 20$$.
a. What will happen to income?
b. Your research assistant comes in and says he's sorry but the mpe wasn't .8; it was .5. How does your answer change?
c. He runs in again and says exports have fallen by $$\$ 10$$ and investment has risen by $$\$ 10$$. How does your answer change?
d. You now have to present your analysis to the president, who wants to see it all graphically. Naturally you oblige. $\mathrm{LO} 2, \mathrm{LO} 3, \mathrm{LO} 4$

Key Concepts

Multiplier Effect

The multiplier effect refers to the process by which an initial change in autonomous spending gets magnified as it circulates through the economy. Essentially, a change in spending leads to increased income, which in turn leads to further spending, resulting in a total impact on national income that is larger than the initial change. This multiplier is typically calculated as 1 divided by (1 minus the marginal propensity to consume/spend).

Marginal Propensity to Consume (MPC) / Marginal Propensity to Expend

This concept captures the proportion of an additional dollar of income that is spent rather than saved. It is a key determinant of the size of the multiplier effect: a higher MPC (or MPE) results in a larger multiplier, which means that any change in autonomous expenditures will have a more significant impact on overall income.

Autonomous Expenditures

Autonomous expenditures are components of aggregate spending that do not depend on the level of current income. These include items such as certain types of government spending, exports, investment, and other exogenous shocks to the economy. Changes in autonomous expenditures shift the aggregate demand curve and create ripple effects in national income through the multiplier mechanism.

Aggregate Expenditure Model

The Aggregate Expenditure Model, a central framework in Keynesian economics, explains how equilibrium income is determined by planned spending in the economy. It integrates the effects of autonomous expenditures, the MPC/MPE, and other factors on aggregate spending, ultimately showing how the economy reaches a level of equilibrium income.

Graphical Analysis (Keynesian Cross Diagram)

The Keynesian Cross diagram is a graphical representation of the relationship between aggregate expenditures and national income. It is used to illustrate equilibrium where aggregate expenditures equal output. Shifts in autonomous expenditures or changes in the MPC/MPE can be visualized in this diagram, making it a useful tool for presenting the multiplier effects and overall income changes.

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