The Number That Keeps Disappointing Finance Ministers
You sign the stimulus bill on a Tuesday. The press release goes out by noon, full of phrases like "historic investment" and "broad-based growth." Your chief economist has a slide deck showing a multiplier of 1.4, maybe 1.6 if the confidence interval smiles on you. Then the quarterly GDP figures land, quiet and unimpressed, and the number that comes back is somewhere around 0.6. Not a rounding error. Not bad implementation. The model was wrong before the ink dried.
That amplification ratio, the fiscal multiplier, describes how much total economic output one dollar of government spending eventually generates. In the closed-economy frameworks that still haunt undergraduate lecture halls, it sits comfortably above 1.5. Spend a hundred dollars per citizen, get a hundred and fifty back in GDP. The construction worker spends her wages at the grocery store, the grocer restocks from the warehouse, the warehouse hires a driver. Each dollar laps the domestic circuit again.
In practice, for most of the world's actually-existing economies, the number lands between 0.5 and 0.9. Sometimes lower.
This is a structural feature of how open economies work, and the models policymakers reach for were not, in their original form, built to capture it.
Where the Money Actually Goes
The core mechanism is straightforward once you see it. In a closed economy, every dollar spent domestically stays in the domestic circuit, attenuated only by whatever fraction households save. The savings rate is the leak in the bucket.
An open economy has a second leak: imports. When a government injects demand, a meaningful share of that demand is satisfied by foreign producers. A household in a small European country receives a transfer payment and spends it on electronics assembled in East Asia, clothing made in South Asia, fuel priced in dollars on global markets. That spending generates income and employment, just not in the country that wrote the check.
Economists call this the import propensity. In small open economies it can be startlingly high; a country where imports represent fifty or sixty percent of GDP will see a large fraction of any demand stimulus leak abroad almost immediately, and the multiplier compresses accordingly.
Consider a worked example with specific numbers. A government borrows to fund infrastructure: ten billion, in a country with a marginal propensity to consume of 0.75 and a marginal propensity to import of 0.35. The standard Keynesian formula gives a multiplier of 1 divided by (1 minus 0.75 plus 0.35), which resolves to 1 divided by 0.60, or roughly 1.67. Sounds decent. But this formula still underestimates the leakage, because it assumes the import propensity applies only to household consumption, not to the capital goods and materials governments themselves import to build the infrastructure. Add government import content of 0.25 on the initial spend, and the effective first-round injection shrinks before the household consumption cycle even begins. Studies of comparable small open economies put the realized multiplier for this type of spending at around 0.6 to 0.8. That gap between the model's promise and the outcome is not a failure of execution. It is baked in, and the following quarter's figures will confirm it.
The Exchange Rate Wrinkle Nobody Wants to Talk About
There is a second channel that even the more sophisticated open-economy extensions handle poorly: the exchange rate response.
When a government runs a larger deficit to fund stimulus, it typically needs to borrow. Borrowing raises domestic interest rates, even modestly. Higher rates attract foreign capital. Foreign capital inflows bid up the domestic currency. A stronger currency makes imports cheaper and exports more expensive, so domestic producers competing with imports face softer demand while export industries watch their margins shrink in foreign markets. This sequence, sometimes called the crowding-out of net exports, can offset a substantial portion of the original demand stimulus.
The Mundell-Fleming model, developed in the early 1960s and still the workhorse for open-economy analysis, predicts this with reasonable clarity: under floating exchange rates and high capital mobility, fiscal policy becomes largely ineffective at boosting output because exchange rate appreciation neutralizes it. The model is not wrong. Policymakers just consistently behave as if they are operating under fixed exchange rates or capital controls, conditions where fiscal multipliers are meaningfully larger, when they are not. That is not an honest mistake at this point. It is a habit of convenience.
Take two hypothetical neighbors: Aldoria and Brentmark. Both run fiscal stimulus of equivalent size during a slowdown. Aldoria has a managed exchange rate and limited capital mobility. Brentmark floats freely and has deep integration with global capital markets. Aldoria sees its multiplier approach 1.2. Brentmark's comes in at 0.55. Same policy, same intent, different institutional context, dramatically different outcome. This is not a hypothetical curiosity. It describes the observable divergence between fiscal outcomes in highly trade-open economies, such as the Nordic countries, versus larger, more domestically self-contained ones where demand circulates more tightly at home.
What People Get Wrong (And Keep Getting Wrong)
The persistent error is treating the fiscal multiplier as a property of the policy itself, not as a property of the economy receiving it.
Ask yourself: how many finance ministry press conferences have you seen cite a multiplier estimate without specifying the exchange-rate regime, the trade-openness ratio, or the monetary policy stance? The academic debates about a multiplier sitting above or below one generate more heat than clarity, partly because both sides are sometimes right, for different countries, different regimes, different positions in the business cycle. A multiplier estimated for a large, relatively closed economy where the central bank was holding rates near zero tells you almost nothing about what a Pacific island economy should expect from a port expansion funded by sovereign borrowing. Applying one figure to the other is like using a tide table from the North Sea to navigate a river delta.
There is also a timing problem that models smooth over. The leakage through imports happens fast: households and firms adjust spending within weeks. The domestic income effects of government expenditure take longer to circulate. So even when the long-run multiplier is positive, the short-run fiscal impulse may disappoint precisely when policymakers are watching most closely, in the quarters immediately following the intervention.
Then there is the composition question, which almost nobody addresses honestly. Spending on tradable goods, computers, vehicles, medical equipment, carries higher import content and therefore a lower multiplier. Spending on non-tradable services, home care, local construction labor, public administration, carries lower import content and a higher multiplier. Governments that announce stimulus packages without attending to this distinction are making an implicit bet on the composition of domestic supply capacity. Sometimes they win.
Often they don't. And the fiscal cost of getting it wrong compounds across multiple quarters.
The Uncomfortable Arithmetic of Openness
None of this means fiscal policy is futile in open economies. It means the mechanism is different, the magnitude is smaller, and the design choices matter enormously. A stimulus package that funds imports is partly a gift to trading partners. That can be fine, even intentional, during global downturns when coordinated expansion is the goal. But it should be understood for what it is, not celebrated as domestic demand creation when the evidence points elsewhere.
The models that politicians cite when they want to justify large spending programs were built for a world with higher trade barriers, lower capital mobility, and less globally integrated supply chains. That world is gone. The fiscal multiplier did not disappear with it, but it got smaller, more conditional, and far more dependent on context.
The real cost of ignoring that is not intellectual. It is the ten billion spent on a multiplier of 0.6, the debt that persists, and the narrower room to maneuver when a fresh downturn arrives and the cupboard is already bare.