Short-Run and Long-Run Aggregate Supply

Chapter 10 companion lesson

A rise in oil prices and an increase in consumer confidence may both change real GDP and the price level, but they enter the AD–AS model from different sides. Correct diagnosis begins with the shocked curve.

Why Short-Run Aggregate Supply Slopes Upward?

Short-run aggregate supply shows real output firms produce at different overall price levels when some wages, input prices, and expectations are slow to adjust. Its upward slope means a higher-than-expected price level can make additional production profitable temporarily.

Sticky wages are one explanation. Labor contracts, norms, and adjustment costs can hold nominal wages fixed for a time. If product prices rise while wages remain unchanged, real labor cost falls and firms hire or use more labor. When wages later adjust, the temporary profit incentive fades.

Sticky prices offer another route. Some firms adjust prices slowly because changing menus, contracts, systems, or customer relationships is costly. Firms whose prices have not yet risen may experience stronger demand and expand output. Imperfect information can also cause producers to mistake a general price-level rise for an increase in their product's relative price.

What Shifts SRAS?

Input prices change firms' production costs. Higher nominal wages, oil prices, imported-input prices, or other costs shift SRAS left. At every overall price level, firms produce less because marginal cost is higher. Lower costs shift SRAS right. A product's selling price is part of the price level and causes movement; an input price is a shifter.

Productivity shifts SRAS right by allowing more output from given inputs and lowering unit cost. Productivity can also expand potential output and shift LRAS right. The short-run and long-run curves may move together, but the reasons should be stated: current cost falls and sustainable capacity rises.

Business taxes and subsidies can affect supply. A tax tied to production cost shifts SRAS left; a subsidy can shift it right. Personal income taxes primarily affect disposable income and AD in the introductory model. The word “tax'' alone is insufficient – identify whose behavior and which cost or spending component changes.

How does the CLEP test potential output and long-run aggregate supply?

Long-run aggregate supply is vertical at potential output. In the long run, wages, prices, and expectations adjust, so a change in the overall price level does not permanently raise real production. Money and the price level can change nominal values, while sustainable real output depends on resources, technology, and institutions.

Potential output corresponds to full employment, not maximum conceivable output with every machine and worker used without rest. It is the sustainable level consistent with normal resource use and the natural rate of unemployment. Actual output can temporarily exceed potential, but labor scarcity, overtime, and rising costs create adjustment pressure.

LRAS shifts right when labor quantity or quality grows, capital accumulates, technology improves, or institutions increase productive capacity. Destruction of capital, persistent labor-force loss, or institutional breakdown can shift it left. A fall in aggregate demand does not itself shift LRAS in the basic model; it moves actual output below the existing potential.

What should you know about demand shocks, supply shocks, and stagflation?

A demand shock moves the price level and real output in the same direction in the short run. AD right raises both; AD left lowers both. A supply shock moves them in opposite directions. SRAS left raises the price level and lowers output; SRAS right lowers the price level and raises output. Observing both variables helps diagnose which curve likely shifted.

Stagflation combines stagnating or falling output with inflation pressure. An adverse supply shock is the standard cause. It challenges policy because expanding AD to restore output raises the price level further, while contracting AD to restrain inflation reduces output further. Supply-side repair or waiting for the shock to reverse may avoid part of the demand-policy tradeoff, but adjustment can be slow or uncertain.

Two shocks can occur together. Currency depreciation may raise net exports and AD while increasing imported-input costs and shifting SRAS left. Both raise the price level; their output effects oppose. A question that gives both mechanisms supports a determinate price increase and indeterminate output unless relative magnitudes are provided.

What is the CLEP likely to ask?

Expect SRAS and LRAS shifts, movement along SRAS from a price-level change, productivity and input-price events, and demand-versus-supply shock diagnosis from price and output directions. A change in the price level alone does not shift SRAS.

A useful check is to name the model before doing arithmetic. Then write the first change, the intermediate market response, and the final macroeconomic result. This keeps a plausible distractor from borrowing one true step and attaching it to the wrong conclusion.

Can you do these without notes?

1. Give three explanations for upward-sloping SRAS. Then distinguish a higher price level, a higher nominal wage, and higher productivity as movement or shifts.
2. Predict the SRAS shift from higher wages, lower energy costs, better productivity, higher expected inflation, a production subsidy, and currency depreciation for an input-importing economy.
3. Classify education, capital formation, a temporary consumption boom, a hurricane that destroys factories, and recovery from a recession as LRAS shifts or movements of actual output relative to fixed potential.

For each prompt, say why the tempting wrong answer fails. That extra sentence is often the difference between recognizing a term and being able to use it under time pressure.