Macroeconomics · Long-Run Consequences of Stabilization Policies · 14 min read · Updated 2026-05-11
Fiscal and Monetary Policy in the Long Run — AP Macroeconomics
AP Macroeconomics · Long-Run Consequences of Stabilization Policies · 14 min read
1. Money Neutrality and the Quantity Theory of Money★★☆☆☆⏱ 4 min
The quantity theory of money is a classical framework linking changes in the money supply to long-run changes in the price level, built on the equation of exchange:
MV = PY
Where $M$ = nominal money supply, $V$ = velocity of money (the average number of times a dollar is spent on final goods and services per year), $P$ = aggregate price level, and $Y$ = real GDP. The product $PY$ equals nominal GDP.
The quantity theory assumes velocity is stable (constant) in the long run, and real GDP is fixed at potential output $Y_p$, independent of the money supply. This follows from the classical dichotomy, which separates nominal and real variables in the long run.
Exam tip: On the AP exam, always assume velocity is constant for quantity theory questions unless the question explicitly states velocity changes.
2. Long-Run Crowding Out★★★☆☆⏱ 3 min
Long-run crowding out is the full offset of private sector spending by government spending that occurs when expansionary fiscal policy is implemented starting from long-run equilibrium at potential output. When the government increases spending or cuts taxes, it runs a budget deficit and borrows in the loanable funds market, increasing demand for loanable funds and raising equilibrium real interest rates. Higher interest rates reduce interest-sensitive private spending, most notably private investment.
In the short run, some increase in output may occur, but over time, output above potential pushes up nominal wages and prices, shifting short-run aggregate supply left until output returns to potential. In the long run, since output is fixed at potential, the entire increase in government spending is offset by a decrease in private spending, resulting in full crowding out.
Exam tip: On FRQs, always explicitly link full long-run crowding out to higher interest rates from government borrowing in the loanable funds market. This link is almost always a required scoring point for full credit.
3. The Long-Run Phillips Curve★★★☆☆⏱ 3 min
The long-run Phillips curve (LRPC) is the relationship between inflation and unemployment after all nominal wages and inflation expectations have adjusted to policy changes. Unlike the downward-sloping short-run Phillips curve (SRPC), which reflects a temporary trade-off between inflation and unemployment due to sticky expectations and wages, the LRPC is a vertical line at the natural rate of unemployment ($u_n$).
A vertical LRPC means there is no permanent trade-off between inflation and unemployment. If policymakers use expansionary policy to raise inflation to lower unemployment, unemployment falls below $u_n$ in the short run, but over time workers adjust their inflation expectations upward, the SRPC shifts up, and unemployment returns to $u_n$ at the new higher inflation rate. Only changes to the natural rate of unemployment shift the LRPC; changes in expected inflation only shift the SRPC.
Exam tip: Always label the horizontal intercept of the LRPC as the natural rate of unemployment, not zero unemployment. Mislabeling this intercept almost always costs a point on AP FRQs.
4. Ricardian Equivalence★★★★☆⏱ 4 min
Ricardian equivalence is a theory of expectations that argues forward-looking consumers internalize the government’s long-run budget constraint, so debt-financed fiscal policy has no effect on aggregate demand even in the short run.
If the government cuts taxes today and finances the cut with debt, consumers know the government will have to raise taxes in the future to pay off the debt plus interest. The present value of future tax increases equals the value of the current tax cut, so consumers do not increase current consumption; instead, they save the entire tax cut to pay future tax liabilities. This means there is no increase in aggregate demand, no change in real interest rates, and no change in output, even in the short run.
Exam tip: Ricardian equivalence only changes consumer response to tax cuts, not to changes in government spending itself. If the question says government increases spending financed by debt, Ricardian equivalence does not eliminate the increase in government spending, only the consumer response to the debt.
Common Pitfalls
Why: Students confuse short-run sticky price effects with long-run full adjustment to potential output
Why: Students mix up the LRAS vertical position at potential output (which corresponds to positive natural unemployment) with the LRPC position
Why: Students carry over partial crowding out from the short run to the long run
Why: Students forget the core assumption of the quantity theory that V is stable in the long run
Why: Students confuse the effect of the tax cut with the government’s spending decision