Q.Why is the open economy autonomous expenditure multiplier smaller than the closed economy one?

The Open Economy Multiplier: From a Village to the World

Imagine a small village where everyone earns by selling goods to each other. If someone gets extra money and spends it at the local shop, the shopkeeper earns more, spends some of that at the tailor, and so on. That chain reaction is the multiplier — an initial spending increase leads to a larger total rise in income.

Now imagine that same village starts selling goods to a nearby town. Some of the money earned from the town stays in the village, but some of it is spent on buying things from the town. That "leakage" weakens the chain reaction. This is the core idea of the open economy multiplier.

What the Open Economy Multiplier Actually Is

In a closed economy (no trade), the multiplier depends only on how much people save out of extra income. The formula is:

where $MPC$ is the marginal propensity to consume (the fraction of extra income spent on domestic goods).

In an open economy, we add two more leakages: spending on imports and the effect of exports. The NCERT textbook gives the precise formula for the open economy multiplier as:

Here:

• $K_O$ = open economy multiplier
• $MPC$ = marginal propensity to consume (fraction of extra income spent on consumption, including imports)
• $MPM$ = marginal propensity to import (fraction of extra income spent on imports)

Notice: $MPC$ here includes spending on both domestic and imported goods. The denominator becomes larger because $MPM$ is added, so $K_O$ is smaller than the closed economy multiplier.

Why It Matters: The Leakage Effect

Think of it this way. In a closed economy, every rupee spent stays within the country and keeps circulating. In an open economy, a part of every rupee spent goes abroad to pay for imports. That money doesn't come back to generate more domestic income.

Example: Suppose $MPC = 0.8$ and $MPM = 0.2$.

• Closed economy multiplier: $K = \frac{1}{1 - 0.8} = 5$
• Open economy multiplier: $K_O = \frac{1}{1 - 0.8 + 0.2} = \frac{1}{0.4} = 2.5$

The same initial spending increase produces only half the income boost when the economy is open. This is why countries with high import dependence have weaker fiscal policy effects — a government spending boost gets "leaked" abroad.

The Role of Exports

Exports work in the opposite direction. When foreigners buy our goods, it's like an injection of spending from outside. The full multiplier in an open economy includes both exports and imports:

where $\Delta X$ is the change in exports. Exports add to aggregate demand just like investment ($I$) or government spending ($G$).

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