Keynesian AS/AD Model: Sticky Wages and Fiscal Policy

Long-run macroeconomic equilibrium occurs where aggregate demand (AD), short-run aggregate supply (SRAS), and long-run aggregate supply (LRAS) all intersect at full employment output (Yf), which corresponds to the natural rate of unemployment with only frictional and structural unemployment present; when a positive demand shock shifts AD to the right, the economy initially moves to a new short-run equilibrium with higher output and prices, but through sticky wage theory—where input prices eventually adjust in the long run—the SRAS curve shifts leftward, returning the economy to full employment output while permanently increasing the price level, demonstrating the classical view of long-run self-adjustment.

This comprehensive macroeconomics lesson covers the critical distinction between short-run and long-run economic analysis. The video explains that general questions about recessions have no single correct answer because outcomes depend on causes (aggregate demand vs supply shifts) and time horizons. Specific questions that identify causes and specify time frames allow definitive answers. In the short run, demand-side changes (government spending, consumer spending, investment) shift aggregate demand, while supply-side changes (wages, currency appreciation, human capital) shift aggregate supply. In the long run, flexible wages and resource prices enable self-correction: economies return to full employment with demand-side changes causing only price adjustments, while investment-driven changes create genuine economic growth through long-run aggregate supply shifts. Permanent destruction shifts supply leftward, reducing productive capacity. Understanding these dynamics is essential for success in macroeconomics courses and standardized tests like the AP Macro exam.

In economics, the distinction between long run and short run concerns flexibility of variables rather than specific time periods. In the long run, all variables (prices, wages, demand) are flexible and markets self-adjust to reach equilibrium. In the short run, wages and other costs are sticky or slow to change, creating temporary imbalances. This distinction explains why economic policies and market outcomes differ based on the timeframe considered.

In the Classical Model: (1) In the short run, savings and investment may not be equal, creating a surplus or shortage; (2) In the long run, savings and investment become equal through adjustments in the interest rate. The interest rate adjusts to balance savings and investment, ensuring long-run equilibrium. This adjustment process is a key mechanism in Classical economics.

The long-run aggregate supply (LRAS) curve represents an economy's productive capacity based on factors of production: capital, labor, and technology. Classical economists view LRAS as a vertical line at potential GDP (YF), indicating full employment with no resource underutilization. They argue wages are completely flexible, enabling automatic market adjustment: when aggregate demand falls, wage cuts reduce costs and restore equilibrium. Keynesians disagree, viewing LRAS as horizontal at mass unemployment, gradually rising, then vertical at full employment. They argue wages are sticky downward—workers resist wage cuts, and employers prefer layoffs. This rigidity prevents automatic adjustment, causing prolonged unemployment and requiring government intervention through fiscal and monetary policy to stabilize the economy.

Fiscal policy uses two basic instruments: government spending (gasto público) and taxation (impuestos). Government spending includes current expenses (salaries, purchases of goods and services, pensions) and capital investments (infrastructure like bridges, roads, hospitals, schools). Taxation represents government revenue. When the state increases spending and decreases taxes, it implements expansionary fiscal policy. When it decreases spending and increases taxes, it implements restrictive fiscal policy.

Fiscal Policy has two main instruments: (1) Government Spending - the government's expenditure on goods and services; (2) Taxation Policy - the government's tax rates and collection. The instructor explains that these two instruments are used to control aggregate demand. When excess demand exists, the government reduces spending and increases taxes. When deficit demand exists, the government increases spending and reduces taxes.

Fiscal policy is the government's use of taxation and spending to influence the economy. The government has the power to collect taxes (arrecadação de tributos) and redistribute resources through public spending. The two basic instruments of fiscal policy are: (1) Taxation policy - the government can increase or decrease tax rates to affect disposable income, and (2) Government spending policy - the government can increase or decrease public expenditures to influence aggregate demand. These tools allow the government to either stimulate or slow down economic activity.

Fiscal policy has two main instruments: (1) Government Spending - includes government purchases and transfer payments, (2) Taxes - includes direct and indirect taxes. Expansionary fiscal policy increases government spending and decreases taxes to stimulate economic growth. Contractionary fiscal policy decreases government spending and increases taxes to control inflation. These instruments are used by the government to manage aggregate demand in the economy.

Fiscal policy has two main instruments: (1) Government Spending - increasing spending stimulates the economy; (2) Taxation - reducing taxes stimulates the economy. Expansionary fiscal policy involves increasing spending or reducing taxes. Contractionary fiscal policy involves decreasing spending or increasing taxes. These tools allow the government to influence aggregate demand and achieve its stabilizing objectives.

In the Aggregate Supply-Aggregate Demand (AS/AD) model, the economy can operate above or below potential output in the short run; a recessionary gap occurs when actual output is less than potential output (AD and SRAS intersect to the left of LRAS), resulting in high unemployment above the natural rate, while an inflationary gap occurs when actual output exceeds potential output (AD and SRAS intersect to the right of LRAS), resulting in low unemployment below the natural rate; in contrast, long-run equilibrium occurs where all three curves intersect at potential output, representing full employment with only structural and frictional unemployment present.

The business cycle consists of four phases: peak (highest economic activity), recession/contraction (falling real GDP), trough (lowest point), and expansion/recovery (rising real GDP). A recessionary gap (negative output gap) occurs when actual GDP falls below potential GDP (full employment level), indicating cyclical unemployment. A positive output gap occurs when actual GDP exceeds potential GDP, leading to inflationary pressures. The full employment line represents potential GDP where only frictional and structural unemployment exist.

A recessionary gap occurs when actual GDP is less than potential GDP, with unemployment below the natural rate. An inflationary gap occurs when actual GDP exceeds potential GDP, with unemployment below the natural rate. In both cases, the economy operates away from its long-run equilibrium. The gap represents the difference between actual and potential output, indicating whether the economy is underperforming or overheating.

GDP gaps represent the difference between actual real GDP and potential GDP. A recessionary gap occurs when real GDP falls below potential GDP, indicating the economy operates below full employment capacity. An inflationary gap occurs when real GDP exceeds potential GDP, creating inflationary pressures. The relationship between aggregate demand and aggregate supply determines which gap exists: when demand exceeds supply, an inflationary gap forms; when supply exceeds demand, a recessionary gap forms.

An output gap measures the difference between actual and potential GDP. A negative output gap (recessionary gap) occurs when actual GDP falls below potential GDP, indicating underutilized resources and high unemployment. A positive output gap (inflationary gap) occurs when actual GDP exceeds potential GDP, leading to inflationary pressures. These terms replace older terminology of recessionary and inflationary gaps used in some textbooks. Note that a recessionary gap doesn't necessarily mean the economy is in a recession - stagflation (high inflation with high unemployment) can occur during a recessionary gap.