Courbes d'Offre et de Demande Agrégées

Aggregate Supply (AS) and Aggregate Demand (AD) Curve Shifts

• The Aggregate Supply (AS) curve shows the relationship between the overall price level and the quantity of goods and services supplied in an economy at any given time.
• The Aggregate Demand (AD) curve represents the relationship between the overall price level and the quantity of goods and services demanded in an economy at any given time.
• Shifts in the AD curve are caused by changes in factors other than the price level, such as government spending, taxes, or consumer confidence.
• Shifts in the AS curve occur due to changes in factors like input costs, technology, and productivity.

Factors Causing AD Shifts

• Changes in Consumer Spending: Increased consumer confidence, more disposable income, and decreased borrowing costs lead to higher aggregate demand, shifting the AD curve to the right. Conversely, decreased consumer confidence, lower disposable income, and increased borrowing costs lead to lower aggregate demand, shifting the AD curve to the left.
• Changes in Investment Spending: Increased business confidence, lower interest rates, and technological advancements encourage investment, boosting aggregate demand, shifting the AD curve to the right. Decreases in any of these factors will shift the AD curve left.
• Changes in Government Spending: Increased government spending (e.g., on infrastructure projects) directly increases aggregate demand, shifting the AD curve to the right. Reduced government spending has the opposite effect.
• Changes in Net Exports: A decrease in net exports (imports exceeding exports) reduces aggregate demand, shifting the AD curve to the left. An increase in net exports from increased exports or decreased imports raises aggregate demand, shifting the AD curve right.

Factors Causing AS Shifts

• Changes in Input Prices: Increased costs of raw materials, labor, or energy raise production costs, leading to a decreased aggregate supply, shifting the AS curve to the left. Decreases in input costs do the opposite, shifting the AS curve to the right.
• Changes in Productivity: Technological advancements and increased worker efficiency increase the aggregate supply, shifting the AS curve to the right. Conversely, slower advancements or decreased worker efficiency lead to a leftward shift.
• Changes in Expected Future Prices: If businesses anticipate a sustained increase in future prices, they might increase current output, lowering immediate costs. This lowers the current AS curve and shifts it rightward.
• Changes in Legal and Regulatory Environment: Easier access to credit or reduced regulations can make production more appealing and efficient, increasing aggregate supply. Conversely, overly burdensome regulations can hinder production and make it less appealing, causing a downward shift in the aggregate supply curve.
• Changes in the Size of the Labor Force: An adequate supply of workers is essential for a given level of output. Shifts in labor supply can affect overall production, leading to changes in aggregate supply.

Interaction of AS and AD Curves

• Equilibrium occurs where the aggregate supply and aggregate demand curves intersect. This intersection determines the overall price level and output in the economy.
• When the AD curve shifts right, the equilibrium point moves to a higher price level and greater output.
• When the AD curve shifts left, the equilibrium point moves to a lower price level and smaller output.
• A rightward shift in the AS curve leads to a lower price level and greater output.
• A leftward shift in the AS curve leads to a higher price level and smaller output.
• Changes in both AS and AD curves influence the economy's overall performance, impacting inflation, unemployment, and economic growth.

Inflationary and Recessionary Gaps

• An inflationary gap occurs when the aggregate demand curve is to the right of the long-run aggregate supply curve at the potential output level, leading to price increases.
• A recessionary gap occurs when aggregate demand is to the left of the long-run aggregate supply curve, resulting in lower output and potentially higher levels of unemployment.
• Policy tools can be used to address these gaps by influencing AD and AS.