Long-Run Consequences of Stabilization Policies

AP Macroeconomics · College Board Unit 5

What this unit covers

• Fiscal policy, automatic stabilisers and the budget balance.
• Deficits, the national debt and why the debt-to-GDP ratio is the measure that matters.
• Crowding out, through both the loanable funds market and the exchange rate.
• Money growth and inflation: the quantity theory and long-run money neutrality.
• The Phillips curve, short run and long run, and the expectations mechanism that connects them.
• Economic growth and the sources of rising productivity.

This is the heaviest unit on the exam, 20–30% of the multiple-choice section, and it is also the unit that ties the others together. Almost everything here is an argument about the same distinction: what demand-side policy can do in the short run, and what it cannot do in the long run. Get that distinction straight and most of the unit follows from it.

Fiscal policy

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Fiscal policy is the use of government spending and taxation to influence aggregate demand.

Note the vocabulary trap. "Expansionary" describes the effect on AD, not on the budget. An expansionary policy shrinks the budget surplus, the two move in opposite directions, and questions exploit that.

The size of the effect

Fiscal policy works through the multipliers from Unit 3, and the exam expects you to apply them rather than just state them.

Spending multiplier = 1 ÷ (1 − MPC)
Tax multiplier = −MPC ÷ (1 − MPC)

A \$100 billion increase in government spending with MPC = 0.75 shifts AD right by 1 ÷ 0.25 × \$100bn = \$400 billion. A \$100 billion tax cut with the same MPC shifts AD right by only 0.75 ÷ 0.25 × \$100bn = \$300 billion, because households save a quarter of the tax cut before any of it is spent.

That gap is the reason spending changes are the more powerful tool per dollar, and the reason a question that says "the government wants to close a \$400bn recessionary gap" has a different answer depending on which instrument it hands you.

Discretionary policy and automatic stabilisers

Discretionary policy requires a deliberate decision, a new spending bill, a change in tax rates.

Automatic stabilisers work without one. In a downturn, incomes fall, so income tax revenue falls automatically while transfer payments such as unemployment benefits rise automatically. Both cushion the fall in disposable income and therefore in AD. In a boom the same mechanisms run in reverse and dampen it.

The two features worth knowing:

• Progressive income taxes stabilise more strongly than flat ones, because revenue falls proportionally faster than income when incomes drop.
• Their decisive advantage is that they act with no policy lag at all. They are already in the law before the recession starts.

Lags

Lags are the main practical weakness of discretionary fiscal policy:

• Recognition lag: data on GDP and unemployment arrive with a delay and get revised, so a recession is identified only after it has begun.
• Decision lag: budgets are annual, and tax and spending changes are politically contested. This lag is much longer for fiscal policy than for monetary policy, where a central bank can act at a scheduled meeting.
• Implementation lag: infrastructure spending in particular takes time to reach the economy.

The consequence is examinable: a stimulus can arrive after the recovery is already under way, at which point it is adding demand to an economy near full employment and is pro-cyclical, it worsens the fluctuation it was meant to dampen.

Reading the budget balance

The budget balance moves with the business cycle even when policy has not changed at all, because tax revenue and transfer payments respond automatically to income. So a deficit that widens in a recession is not evidence of expansionary policy.

• The cyclical component is the part of the balance caused by the economy's position relative to full employment.
• The structural component is what the balance would be at full employment, the part that reflects actual policy decisions.

A question that asks whether the government has "loosened fiscal policy" is asking about the structural part.

Deficits and the national debt

Keep the two apart, because the distinction is tested directly:

• A budget deficit is a flow: spending minus revenue over a period, usually a year.
• The national debt is a stock: the accumulated total of past deficits, minus past surpluses.

It follows that a government can reduce its deficit every year for a decade while its debt rises every year for that same decade. The debt only falls when the budget is in surplus.

The ratio, not the level. What matters for sustainability is debt as a percentage of GDP, because GDP measures the income out of which the debt is serviced. This has a useful implication: if nominal GDP grows faster than the debt, the ratio falls even though the debt is still rising in dollar terms.

Why sustained debt is a long-run problem in AP terms:

• Interest payments absorb a growing share of the budget, displacing other spending.
• Persistent borrowing raises real interest rates and crowds out private investment, which is the mechanism the next section develops.
• A smaller capital stock means lower productivity and a slower-growing LRAS in the future.

Why it is not automatically a crisis. Debt held domestically is owed by a country partly to itself, the interest is a transfer between citizens, not a loss of national income. Debt held abroad is a genuine claim on future output. And borrowing that finances investment in infrastructure, education or R&D can raise future potential output by more than the debt costs. The examiner rewards the distinction between borrowing to invest and borrowing to consume.

Crowding out

This is the direct link between fiscal policy and the loanable funds market from Unit 4, and it is one of the most heavily tested chains in the course.

The government runs a deficit → it borrows → the demand for loanable funds shifts right → the real interest rate rises → private investment falls.

On the loanable funds diagram, the vertical axis is the real interest rate and the horizontal axis is the quantity of loanable funds. Government borrowing is an increase in demand for funds, so the demand curve shifts right, the equilibrium real interest rate rises, and the higher rate makes fewer private investment projects profitable.

The FRQ chain usually asks for two or three graphs, loanable funds → AD/AS, sometimes with the money market as well. Draw them in that order, and carry the result of each into the next.

How severe is it?

Crowding out is not all-or-nothing, and saying so is worth marks:

• With substantial spare capacity and idle saving, extra government borrowing raises the real interest rate only slightly, so little investment is displaced. In a deep recession the effect can be close to negligible.
• Near full employment, saving is already fully employed, the interest-rate rise is much larger, and the displacement of private investment is correspondingly larger.

There is also a case running the other way. If government spending on infrastructure raises the expected return on private capital, private investment demand can rise alongside it, crowding in. AP treats this as the exception rather than the rule, but it is the reason "crowding out is automatic" is a wrong answer.

The open-economy channel

The higher real interest rate does not only affect domestic investment, and this connection to Unit 6 appears regularly:

Real interest rate rises → the return on domestic financial assets rises → financial capital flows in from abroad → demand for the domestic currency rises → the currency appreciates → exports become dearer and imports cheaper → net exports fall.

So a budget deficit crowds out investment and net exports, both of which are components of AD, and both of which partly offset the original stimulus.

The long-run consequence

Investment is what adds to the capital stock. Sustained crowding out therefore means a smaller capital stock in the future, lower labour productivity, and slower growth of potential output, LRAS shifts right by less than it otherwise would. That is the "long-run consequence" this unit is named for.

Money growth and inflation

The long-run relationship between the money supply and the price level is expressed by the equation of exchange:

M × V = P × Y

where M is the money supply, V the velocity of money (how many times a dollar is spent in a year), P the price level and Y real output.

The equation is an identity, true by definition. It becomes the quantity theory of money, a theory with a prediction, once two assumptions are added:

• V is roughly stable in the long run, being determined by payment habits and institutions.
• Y is at its full-employment level in the long run, determined by real factors, exactly the assumption that makes LRAS vertical.

With V and Y fixed, any increase in M must show up in P:

% change in M ≈ % change in P (in the long run)

If the money supply grows 10% a year while real output grows 3%, the long-run inflation rate is roughly 7%.

Money neutrality is the conclusion: in the long run, changes in the money supply affect nominal variables, the price level, nominal wages, nominal GDP, and leave real variables, real output, employment, real wages, unchanged. This is the monetary counterpart of the vertical LRAS and the vertical LRPC, and all three say the same thing in different notation.

In the short run money is not neutral. Sticky wages and prices mean an increase in the money supply lowers the real interest rate, raises investment and raises real output. The short run is where monetary policy works; the long run is where it only moves prices.

Hyperinflation is the extreme case, and it is always a monetary phenomenon: a government that cannot raise enough tax revenue prints money to pay its bills, M grows explosively, and P follows. It is also the case where V stops being stable, people spend money as fast as they receive it to avoid holding a depreciating asset, which raises V and makes the inflation worse still.

The Phillips curve

The short-run Phillips curve (SRPC) shows an inverse relationship between the inflation rate and the unemployment rate. It is not a separate theory: it is the AD–AS model replotted. When AD rises, output rises and unemployment falls, while the price level rises, lower unemployment alongside higher inflation is exactly a movement along a downward-sloping SRPC.

The reason the trade-off exists in the short run is sticky nominal wages. Wages are fixed by contracts and expectations formed in the past, so a rise in the price level cuts the real wage, makes hiring more profitable, and raises employment.

The long-run Phillips curve (LRPC) is vertical at the natural rate of unemployment. It is the Phillips-curve counterpart of vertical LRAS, and the two must always agree.

The natural rate of unemployment (NRU) is the unemployment that remains when the economy is at full employment: frictional unemployment (people between jobs) plus structural unemployment (skills or location mismatch). It excludes cyclical unemployment, which is what an output gap creates. At the natural rate, cyclical unemployment is zero, full employment does not mean zero unemployment.

The correspondence AP tests

The expectations mechanism

This is the heart of the unit:

Expansionary policy raises AD → the economy moves up-left along the SRPC, so unemployment falls below the natural rate and inflation rises → workers and firms revise their inflation expectations upward → nominal wages are bargained higher → SRAS shifts left and the SRPC shifts right → unemployment returns to the natural rate at a permanently higher inflation rate.

So in the long run there is no trade-off: the economy ends back on the LRPC, with the same unemployment and higher inflation. That is the single most commonly missed conclusion in this unit.

The expectations are adaptive, people revise what they expect on the basis of the inflation they have actually experienced. That is why the adjustment takes time, and why the short-run trade-off is real while it lasts.

Disinflation runs the mechanism in reverse and is worth rehearsing, because it explains why reducing inflation is costly. Contractionary policy shifts AD left; the economy moves down-right along the SRPC, so inflation falls but unemployment rises above the natural rate. Only once expectations of inflation fall does the SRPC shift left, returning unemployment to the natural rate at the lower inflation rate. The temporary rise in unemployment is the price of the permanent fall in inflation.

What shifts the LRPC. Only a change in the natural rate itself, better job-matching, retraining that reduces structural unemployment, or changes in labour-market institutions. Demand-side policy never shifts it. Since growth shifts LRAS right and the LRPC left, the two always move together.

Stagflation appears here as a rightward shift of the SRPC: higher inflation and higher unemployment at the same time, caused by a negative supply shock.

Economic growth

Long-run growth means an outward shift of the PPC and a rightward shift of LRAS, an increase in the economy's productive capacity, Yf.

Distinguish it from recovery. Moving from inside the PPC back to the frontier, or closing a recessionary gap, raises measured output but is not economic growth: capacity never changed. Only a shift of the frontier is growth.

The sources:

• growth in the labour force, through population, immigration or participation
• human capital: education, training, health
• investment in physical capital, which is why the saving and investment channel matters
• technological progress, usually the largest long-run contributor
• institutions: secure property rights, enforceable contracts, the rule of law

Productivity, output per worker per hour, is the underlying driver of living standards. Population growth raises total GDP; only productivity growth raises GDP per capita, and it is per capita income that measures whether people are better off.

Policies that promote growth: public investment in infrastructure, education and R&D; protecting property rights; tax and interest-rate conditions that encourage saving and investment; and avoiding sustained crowding out.

The connection this unit insists on: demand-side policy affects output in the short run only. Once expectations adjust, output returns to Yf. Only supply-side improvements move Yf itself.

Worked example

An economy is at full employment. The government cuts taxes sharply, financing the cut by borrowing. MPC = 0.8.

The size of the stimulus.

Tax multiplier = −0.8 ÷ (1 − 0.8) = −4

A \$50 billion tax cut therefore shifts AD right by \$200 billion.

Short run.

Disposable income rises → consumption rises → AD shifts right → because the economy was already at Yf, it moves up the steep portion of SRAS, so most of the effect falls on the price level → on the Phillips diagram, the economy moves up and to the left along the SRPC, so unemployment falls below the natural rate and inflation rises.

Long run.

With unemployment below the natural rate, labour markets are tight → workers expect higher inflation and bargain for higher nominal wages → input costs rise → SRAS shifts left and the SRPC shifts right → output returns to Yf and unemployment returns to the natural rate, but at a higher inflation rate than before.

The conclusion. The tax cut bought a temporary fall in unemployment at the cost of permanently higher inflation. Because it stimulated demand rather than capacity, Yf and the LRPC did not move.

Now add the fiscal consequence. The tax cut widens the deficit, so government borrowing rises, the demand for loanable funds shifts right, the real interest rate rises, and private investment is crowded out. The higher real rate also attracts financial capital from abroad, appreciating the currency and reducing net exports. Over time, the lower investment slows the growth of the capital stock and therefore of potential output, so a policy aimed at the short run has left the long-run position slightly worse.

Second worked example: reading a disinflation

Inflation is running at 9% and unemployment at 3%, against a natural rate of 5%. The central bank raises the policy rate sharply.

AD shifts left → the economy moves down and to the right along the SRPC: inflation falls, and unemployment rises above 5%. On the AD–AS diagram this is a recessionary gap.

As the lower inflation persists, expectations adjust downward → nominal wage growth slows → SRAS shifts right and the SRPC shifts left → unemployment returns to 5%, now at the lower inflation rate.

The examinable point: the economy ends at the natural rate either way. What the policy changed permanently is the inflation rate, and what it changed temporarily is unemployment.

Common exam mistakes

• Drawing the LRPC as downward-sloping. It is vertical at the natural rate.
• Shifting the SRPC when the correct answer is a movement along it. Any AD change moves the economy along the SRPC; only supply shocks and changed expectations shift it.
• Failing to make the AD–AS and Phillips-curve diagrams agree. They describe the same event and must tell the same story.
• Claiming a permanent unemployment–inflation trade-off.
• Treating crowding out as automatic regardless of spare capacity.
• Confusing the budget deficit (a flow) with the national debt (a stock).
• Assuming a widening deficit proves policy has loosened, when the cause may be cyclical.
• Shifting LRAS or the LRPC for a demand-side policy.
• Saying full employment means zero unemployment. It means zero cyclical unemployment.
• Applying money neutrality to the short run. In the short run money changes real output.
• Calling a movement from inside the PPC back to the frontier "economic growth".
• Using the spending multiplier for a tax change.

Exam technique

Expect to draw side-by-side AD–AS and Phillips-curve diagrams, and make them consistent: if AD shifts right, the Phillips diagram shows a movement along the SRPC, not a shift. Examiners mark the pair together.

Label the Phillips axes Inflation Rate and Unemployment Rate, mark the natural rate on the horizontal axis, and draw the LRPC vertical through it. On the loanable funds diagram, label the axes Real Interest Rate and Quantity of Loanable Funds, not "price" and "quantity", and not the nominal rate.

For long-run questions, always run the expectations step explicitly. The marks are in the mechanism, and the final position on the LRPC is the conclusion the question wants. Writing "in the long run unemployment returns to the natural rate" without the wage-adjustment chain that gets it there scores the conclusion but not the reasoning.

When a question chains fiscal policy into crowding out. State the direction of each shift and the variable it changes at every step: demand for loanable funds right, real interest rate up, investment down, capital stock smaller, LRAS growth slower. Each link is typically its own rubric point, and skipping the intermediate steps loses them even when the final answer is right.

Quick revision

• Automatic stabilisers act with no lag; discretionary policy has recognition, decision and implementation lags.
• Deficit = flow; national debt = stock. Sustainability is judged by debt ÷ GDP.
• Crowding out: deficit → LF demand right → real rate up → investment down → slower long-run growth.
• The same rate rise attracts capital inflows → currency appreciates → net exports fall.
• Crowding out is small with spare capacity, large near full employment.
• MV = PY; with V and Y stable, %ΔM ≈ %ΔP. Money is neutral in the long run, not the short run.
• SRPC slopes down because nominal wages are sticky; LRPC is vertical at the natural rate.
• Natural rate = frictional + structural. Full employment means zero cyclical unemployment.
• AD change → movement along the SRPC. Supply shock or changed expectations → SRPC shifts.
• Long run: expectations adjust, SRAS shifts, unemployment returns to natural, inflation is permanently higher.
• Disinflation costs a temporary rise in unemployment above the natural rate.
• LRAS right ⇔ LRPC left. Growth comes from labour, capital, human capital, technology and institutions.
• Growth means shifting the PPC outward, not returning to it.