Unit 5 Stabilization Policies: Short-Run Demand Management and Long-Run Inflation Tradeoffs

Fiscal and Monetary Policy Actions in the Short Run

What “stabilization policy” is trying to do

In AP Macroeconomics, stabilization policies are government actions meant to reduce the size of business-cycle fluctuations—recessions (high unemployment, low output) and booms (low unemployment, overheating, rising inflation). The key idea is that in the short run, the economy can deviate from its potential output (also called full-employment output), because some prices—especially wages—are sticky and do not adjust instantly.

To analyze short-run effects, you mainly use the AD–AS model:

• Aggregate demand (AD) represents total planned spending on domestic output at each price level.
• Short-run aggregate supply (SRAS) is upward sloping because many input prices (like wages) adjust slowly.
• Long-run aggregate supply (LRAS) is vertical at potential output because in the long run, output is determined by resources and technology—not the price level.

Stabilization policy mostly works by shifting AD in the short run. That’s the core “mechanism” you’re expected to explain on AP exam graphs and in written reasoning.

Short-run fiscal policy: what it is, why it matters, how it works

Fiscal policy is the use of government spending and taxation (set by Congress and the President) to influence the economy.

Expansionary vs. contractionary fiscal policy

• Expansionary fiscal policy increases AD to fight a recessionary gap.
  • Increase government spending (often written as an increase in G)
  • Decrease taxes (often written as a decrease in T)
• Contractionary fiscal policy decreases AD to cool an inflationary gap.
  • Decrease G
  • Increase T

Why this matters: fiscal policy is one of the main tools the government has to push the economy toward full employment in the short run. But it can also create long-run consequences—especially if it changes deficits and debt or if it contributes to persistent inflation.

The AD–AS transmission mechanism for fiscal policy

In the AD–AS model:

1. An increase in government spending directly raises total spending.
2. A tax cut increases disposable income, which tends to raise consumption.
3. Higher total spending shifts AD right.
4. In the short run, with sticky wages, firms respond by producing more—so real GDP rises and the price level rises.

So the usual short-run outcome of expansionary fiscal policy is:

• Higher output (lower unemployment)
• Higher price level (upward pressure on inflation)

A key subtlety: fiscal policy can also affect interest rates through loanable funds. When the government runs larger deficits, it borrows more, which can raise interest rates and crowd out some private investment. On the AP exam, you should be ready to explain crowding out qualitatively or with the loanable funds graph (higher government borrowing shifts demand for loanable funds right, raising real interest rates).

Automatic stabilizers vs. discretionary fiscal policy

• Automatic stabilizers are features of the budget that automatically move fiscal policy in a countercyclical direction without new laws.
  • Progressive income taxes: in a recession, incomes fall, tax collections fall, and that cushions the fall in disposable income.
  • Unemployment insurance and transfer programs: payouts rise in recessions, supporting consumption.
• Discretionary fiscal policy requires deliberate policy changes (new spending bills or tax laws).

Automatic stabilizers matter because they reduce the size of economic swings even when political decision-making is slow.

Short-run monetary policy: what it is, why it matters, how it works

Monetary policy is the central bank’s management of the money supply and interest rates. In the United States, this is done by the Federal Reserve (the Fed).

Expansionary vs. contractionary monetary policy

• Expansionary monetary policy increases the money supply and tends to lower nominal interest rates to increase AD.
• Contractionary monetary policy decreases the money supply and tends to raise nominal interest rates to decrease AD.

Why this matters: monetary policy is often faster to implement than fiscal policy and is the standard tool used to manage inflation and stabilize output.

The monetary transmission mechanism (step-by-step)

AP Macroeconomics expects you to explain a chain like this:

1. The Fed increases the money supply.
2. With more money available, interest rates tend to fall.
3. Lower interest rates increase interest-sensitive spending, especially investment (and sometimes consumption on big-ticket items).
4. Higher spending shifts AD right.
5. In the short run, output and the price level rise.

In reverse, contractionary policy tends to raise interest rates, reduce investment, shift AD left, lower output, and reduce inflation pressure.

How the Fed changes the money supply (tools)

The AP course emphasizes three tools:

• Open market operations (OMO): the Fed buys or sells government securities.
  • Buying securities increases bank reserves and increases the money supply.
  • Selling securities decreases reserves and decreases the money supply.
• Reserve requirement: the fraction of deposits banks must hold as reserves.
  • Lowering it can increase money creation; raising it can reduce money creation.
• Discount rate: the interest rate the Fed charges banks for loans.
  • Lowering it encourages borrowing from the Fed; raising it discourages borrowing.

In practice, OMOs are the most commonly discussed and the cleanest for AP-style cause-and-effect reasoning.

Putting fiscal vs. monetary policy “in action” with AD–AS

You should be able to look at a scenario (recessionary gap or inflationary gap) and choose a policy, then show the short-run outcome.

Example 1: Recessionary gap and expansionary policy

Suppose real GDP is below potential (high unemployment). The government chooses expansionary fiscal policy by increasing G.

• AD shifts right.
• Real output rises toward potential.
• The price level rises.

If the Fed instead uses expansionary monetary policy:

• Money supply rises, interest rates fall.
• Investment rises.
• AD shifts right.
• Output rises and price level rises.

A common misconception is to think “expansionary policy lowers the price level because it helps the economy.” In the AD–AS framework, expansionary policy typically raises the price level in the short run because demand increases faster than sticky input prices adjust.

Example 2: Inflationary gap and contractionary policy

Suppose real GDP is above potential (the economy is overheating). The Fed uses contractionary monetary policy.

• Money supply falls, interest rates rise.
• Investment falls.
• AD shifts left.
• Output falls toward potential and the price level rises more slowly or falls (disinflation can occur).

What goes wrong: lags and unintended consequences

Even if the model is correct, policy can be messy in reality.

• Inside lags: time to recognize the problem and implement policy (often larger for fiscal policy).
• Outside lags: time for policy to affect spending and production (can be significant for monetary policy).
• Crowding out: expansionary fiscal policy can raise interest rates and reduce private investment, limiting the increase in AD.

These are not excuses to avoid the model—on AP, you use the model first, then add one well-placed sentence about lags or crowding out if asked.

Exam Focus

• Typical question patterns:
  • “The economy is in a recessionary gap. Show an appropriate fiscal or monetary policy on an AD–AS graph and explain the effects on real GDP, unemployment, and the price level.”
  • “Explain how open market operations affect the money supply, interest rates, investment, and aggregate demand.”
  • “Use the loanable funds market to show how a budget deficit can affect real interest rates and investment.”
• Common mistakes:
  • Mixing up directions: expansionary policy shifts AD right (not left), and usually raises the price level in the short run.
  • Saying “the Fed controls investment directly.” The Fed primarily changes interest rates and money conditions; investment responds.
  • Forgetting crowding out for fiscal expansion when asked about interest rates or long-run growth implications.

The Phillips Curve

What the Phillips Curve is

The Phillips Curve is a model that shows a relationship between inflation and unemployment. In AP Macro, it’s mainly used to think about tradeoffs (and limits to tradeoffs) when policymakers try to stabilize the economy.

There are two key versions:

• The short-run Phillips curve (SRPC): typically downward sloping—when unemployment is lower, inflation tends to be higher.
• The long-run Phillips curve (LRPC): vertical at the natural rate of unemployment—in the long run, there is no stable tradeoff between inflation and unemployment.

Why it matters (and how it connects to AD–AS)

The Phillips Curve is another way to describe what you already see in AD–AS:

• When AD increases, output rises above potential and unemployment falls below the natural rate—but the price level rises faster, creating inflation pressure.
• When AD decreases, output falls below potential and unemployment rises—but inflation pressure falls.

So you can think of the SRPC as a “short-run outcomes menu”: different levels of demand imply different combinations of unemployment and inflation.

How the short-run Phillips curve works

In the short run, wages and expectations do not fully adjust. If firms face stronger demand, they raise production and hire more workers—unemployment falls. But as the economy heats up, firms raise prices and wages begin to rise, producing higher inflation.

This helps explain the typical downward slope: lower unemployment is associated with higher inflation, and higher unemployment with lower inflation.

A crucial clarification: the SRPC is usually about inflation, not the price level. In AD–AS, you often track the price level; in Phillips Curve analysis, you focus on how rapidly prices are changing.

The natural rate of unemployment and the long-run Phillips curve

The natural rate of unemployment is the unemployment rate consistent with the economy producing at potential output. It includes frictional and structural unemployment (not cyclical unemployment).

In the long run, unemployment tends to return to this natural rate because wages and expectations adjust. That’s why the LRPC is vertical: you can have high inflation or low inflation in the long run, but unemployment gravitates back to the natural rate.

Expectations and shifts of the SRPC

The SRPC can shift. The most important shifter in AP Macro is expected inflation.

If people expect higher inflation, workers negotiate higher nominal wages and firms raise prices more aggressively—so for any given unemployment rate, inflation ends up higher. That shifts the SRPC up.

If expected inflation falls, the SRPC shifts down.

This is the logic behind why repeated demand stimulus can lead to a worse inflation outcome over time: policy that keeps pushing unemployment below the natural rate can cause expectations to rise, shifting SRPC upward.

Supply shocks, stagflation, and the Phillips Curve

A negative supply shock (like a large increase in key input costs) can raise inflation and raise unemployment at the same time. In AD–AS, that’s a left shift of SRAS. In Phillips Curve terms, it shifts SRPC up and to the right—worse inflation at every unemployment rate.

This situation is often called stagflation (stagnation plus inflation). It matters because it breaks the simple “pick a point on the curve” intuition. If the curve shifts, policymakers face a more painful tradeoff.

“In action” examples

Example 1: Demand-driven fall in unemployment

Suppose the Fed uses expansionary monetary policy and AD rises.

• In AD–AS: real GDP rises above potential and the price level rises faster.
• In Phillips Curve terms: the economy moves along the SRPC to a point with lower unemployment and higher inflation.

Example 2: Rising inflation expectations

Suppose the government repeatedly uses expansionary policy to keep unemployment below the natural rate.

• Short run: unemployment stays low, but inflation rises.
• Over time: expected inflation increases, shifting SRPC up.
• Long run: unemployment returns to the natural rate, but inflation is now higher.

A common student error is to claim that the long-run Phillips curve slopes downward “because low unemployment always causes inflation.” The AP long-run story is that expectations adjust, eliminating a permanent tradeoff.

Example 3: Supply shock (stagflation)

Imagine a sudden increase in oil prices.

• Firms’ costs rise, so they raise prices and cut output.
• Inflation rises while unemployment rises.
• SRPC shifts up/right.

If you only memorize “inflation and unemployment move opposite,” this example exposes the misconception. They can rise together when the short-run curve shifts.

Exam Focus

• Typical question patterns:
  • “Use a Phillips curve to show the short-run effect of an expansionary monetary policy on inflation and unemployment.”
  • “Explain how expected inflation affects the short-run Phillips curve and the long-run outcome of repeated demand stimulus.”
  • “Describe and illustrate stagflation using either AD–AS or the Phillips curve (and often both).”
• Common mistakes:
  • Confusing movements along SRPC (caused by demand changes) with shifts of SRPC (caused by expectations or supply shocks).
  • Treating the LRPC as downward sloping; on AP it is vertical at the natural rate.
  • Using the price level instead of inflation when interpreting the Phillips curve.

Money Growth and Inflation

What inflation is (and what it isn’t)

Inflation is a sustained increase in the overall price level. It is not “prices are high”—it’s “prices are rising over time.” This distinction matters because policies aimed at reducing inflation are about slowing the rate of increase, not necessarily pushing the price level back down.

Economists often connect persistent inflation to persistent growth in the money supply. The basic logic is: if the amount of money people have to spend grows much faster than the amount of goods and services the economy produces, prices tend to rise.

The quantity theory of money: the core model

A standard model linking money and prices is the quantity equation:

M V = P Y

Where:

• M is the money supply
• V is the velocity of money (how often a typical dollar is spent in a period)
• P is the price level
• Y is real output (real GDP)

Why it matters

This equation is a central bridge between monetary policy and long-run inflation. It supports a key AP idea: in the long run, inflation is closely related to money growth (especially when velocity is stable and real output growth is determined by real factors).

How to use it (the growth-rate form)

AP questions often use a growth-rate interpretation. Taking percentage changes gives:

\%\Delta M + \%\Delta V = \%\Delta P + \%\Delta Y

Interpreting each term:

• \%\Delta P is the inflation rate
• \%\Delta Y is real GDP growth

If velocity is stable (so \%\Delta V is about zero), then:

\%\Delta P \approx \%\Delta M - \%\Delta Y

This approximation is extremely useful for exam-style numeric reasoning.

How money growth can create inflation (mechanism, not just a formula)

To really understand the claim “money growth causes inflation,” keep the causal story in mind:

1. The central bank increases the money supply persistently.
2. Households and firms have more money relative to the quantity of goods and services available.
3. Total spending rises.
4. Over time, wages and prices adjust upward.
5. In the long run, real output returns to potential (determined by resources and technology), but the price level ends up higher—meaning sustained money growth shows up as sustained inflation.

This is closely tied to the AP concept of long-run monetary neutrality: in the long run, changes in money growth mainly affect nominal variables (like the price level and nominal wages) rather than real variables (like real GDP).

Connecting money growth to stabilization policy (Unit 5 logic)

In Unit 5, the big takeaway is about long-run consequences:

• Expansionary monetary policy can reduce unemployment in the short run.
• But if money growth is maintained too high for too long, it can create higher ongoing inflation.

This connects directly to the Phillips Curve story: pushing demand to keep unemployment below the natural rate tends to raise inflation and, if repeated, can raise expected inflation and shift the SRPC upward.

“In action” worked examples

Example 1: Compute inflation from money growth

Suppose the money supply grows at 8% per year and real GDP grows at 3% per year. Assume velocity is constant.

Using:

\%\Delta P \approx \%\Delta M - \%\Delta Y

Substitute values:

\%\Delta P \approx 8\% - 3\% = 5\%

Interpretation: inflation is approximately 5%.

Common mistake to avoid: adding the growth rates instead of subtracting, or forgetting that real GDP growth “absorbs” some of the increased money.

Example 2: Velocity changes (why the approximation can fail)

Suppose \%\Delta M = 6\%, \%\Delta Y = 2\%, but velocity falls by 1% (so \%\Delta V = -1\%).

Use the full growth-rate equation:

\%\Delta M + \%\Delta V = \%\Delta P + \%\Delta Y

Compute left side:

6\% + (-1\%) = 5\%

Now solve for inflation:

\%\Delta P = 5\% - 2\% = 3\%

So inflation is 3%, not 4%. This shows why velocity assumptions matter.

Money growth vs. one-time price increases

Another common misconception is to treat any rise in prices as “inflation caused by money.” A one-time supply shock (like a sudden rise in oil prices) can raise the price level and even raise inflation temporarily, but sustained inflation usually requires ongoing forces—often persistent growth in money or sustained demand growth.

In AP terms:

• Demand-pull inflation: persistent rightward pressure on AD (often connected to monetary expansion).
• Cost-push inflation: rising costs shifting SRAS left (often linked to supply shocks).

Policy tradeoffs: disinflation and credibility (conceptual)

If inflation expectations have risen, reducing inflation often requires contractionary monetary policy that slows demand. In the short run, this can raise unemployment—this is the classic short-run cost of disinflation implied by the Phillips Curve framework. AP questions may ask you to explain why lowering inflation can increase unemployment in the short run.

While AP does not require deep institutional detail, the general logic is testable: expectations matter. If people believe the central bank is committed to low inflation, expected inflation may fall more quickly, shifting SRPC down and making disinflation less costly than if expectations are “stuck” at high levels.

Exam Focus

• Typical question patterns:
  • “Using the quantity equation, calculate the inflation rate given money growth and real GDP growth (sometimes including velocity).”
  • “Explain why persistent money growth leads to inflation in the long run, using AD–AS or the quantity theory.”
  • “Connect expansionary monetary policy to short-run unemployment changes and long-run inflation (often tying to the Phillips curve).”
• Common mistakes:
  • Confusing the price level with inflation—money growth relates most cleanly to sustained inflation, not a one-time jump in prices.
  • Forgetting the role of real GDP growth (and sometimes velocity) when using M V = P Y.
  • Claiming monetary policy permanently increases real GDP; in AP’s long-run framework, output returns to potential while prices adjust.