Chapter 13 · Demand-side and supply-side policies
Contractionary demand-management policy
Show how contractionary fiscal or monetary policy shifts AD left to reduce inflationary pressure. Explain the possible cost to output and employment.
The economic idea
Macroeconomic policy uses demand-side and supply-side measures to pursue objectives such as stable prices, low unemployment, sustainable growth and a stable external position. Demand-side policy changes aggregate demand; supply-side policy changes productive capacity, efficiency or the natural rate of unemployment.
Fiscal policy is the use of government expenditure and taxation to influence aggregate demand, resource allocation and income distribution. Discretionary fiscal policy is a deliberate change, while automatic stabilizers such as progressive taxation and unemployment benefits respond without a new policy decision.
Monetary policy is action by a central bank to influence financial conditions and aggregate demand. Conventional policy changes a policy interest rate; other measures include asset purchases, credit facilities, reserve tools and communication about future policy.
Expansionary policy raises aggregate demand through higher government expenditure, lower taxation, lower interest rates or easier credit. Contractionary policy lowers aggregate demand through the opposite changes. The appropriate stance depends on the output gap and the source of inflation or unemployment.
Demand management cannot directly remove structural unemployment or permanently increase productive capacity. Supply-side policies may complement it, but usually operate through different channels and longer time horizons.
Reading the current policy movement from AD₁ to AD₂
“Price level” is measured vertically and “Real GDP” horizontally.
“AD₁” records initial planned expenditure and “AD₂” the current post-policy level. “SRAS” is held fixed.
“LRAS” marks potential output. “E₁” and “E₂” identify the initial and post-policy macroeconomic equilibria.
Initial condition: E₁
“AD₁” intersects “SRAS” at “E₁”, establishing “Y₁” and “PL₁”. Relative to “LRAS”, the economy initially shows an inflationary gap.
Policy movement: AD₁ to AD₂
“AD₂” lies to the left of “AD₁”. Real GDP falls from “Y₁” to “Y₂”, while the price level falls from “PL₁” to “PL₂”. “E₂” lies at “LRAS”, so the output gap is closed in the current state.
Post-policy equilibrium: E₂
“AD₂” intersects the unchanged “SRAS” at “E₂”, establishing “Y₂” and “PL₂”. “E₂” lies at “LRAS”, so the output gap is closed in the current state.
Link weaker expenditure to the policy trade-off
Lower government spending reduces G directly. Higher income tax can reduce disposable income and consumption; higher interest rates can reduce borrowing and interest-sensitive consumption and investment. Each route can weaken AD through a different first step.
Reducing demand pressure may help control inflation, but weaker sales can also reduce output and employment in the short run. Evaluate the starting output gap and the source of inflation before treating that cost as either unavoidable or irrelevant.
From a policy decision to the current AD–AS outcome
A fiscal authority reduces expenditure or raises taxes, or a central bank tightens financial conditions.
Consumption, investment, government spending or net exports decrease, shifting aggregate demand from “AD₁” toward “AD₂”.
Firms respond to the change in planned expenditure by moving along “SRAS”, altering output, employment and the price level.
Common mistakes to avoid
- “AD₂” is not automatically expansionary or contractionary because of the page title; its position relative to “AD₁” determines the direction shown.
- Closing a gap means moving equilibrium output toward “LRAS”, not merely shifting “AD₁” by a large distance.
- Fiscal and monetary policy can produce a similar AD shift but use different instruments, institutions and transmission channels.
- A reduction in the price level in a comparative-equilibrium diagram is not automatically a sustained fall in the inflation rate over time.
- The model does not show the budget balance, public debt, policy interest rate, exchange rate or distributional effects.
How to draw this diagram
- Title the diagram “Contractionary demand-management policy”. Label the horizontal axis “Real GDP” and the vertical axis “Price level”.
- Draw AD₁ first and label it clearly.
- Draw SRAS next and label it clearly.
- Draw AD₂ next and label it clearly.
- Draw LRAS next and label it clearly.
- Mark each relevant intersection and distinguish the initial, market and socially optimum or policy outcomes where applicable.
- Project important intersections to the axes with dashed guide lines and label the outcomes.
- Check that every symbol used in the explanation appears on the diagram and add arrows showing the direction of change.
Assumptions and limitations
- The diagram combines many possible fiscal and monetary instruments into one aggregate-demand shift and cannot identify which instrument was used.
- It compares equilibria rather than showing recognition, decision, implementation and impact lags.
- Potential output and SRAS are held fixed even though investment, hysteresis, commodity prices and expectations can change them.
- Multiplier, exchange-rate, financial-stability, public-debt and distributional effects are not plotted.
- The model does not determine the optimal policy mix or prove that the estimated output gap is correct.