Real GDP and the Price Level in the Short Run (Chapter 8 Study Notes)

Real GDP and the Price Level in the Short Run

Chapter Overview

This chapter examines the relationship between real GDP and the price level in the short run, focusing on the aggregate demand and aggregate supply framework. Students will learn how changes in the price level affect aggregate expenditure, the derivation and shifts of the aggregate demand (AD) curve, and the supply side of the economy.

8.1 The Demand Side of the Economy

Exogenous Changes in the Price Level

Exogenous changes in the price level can significantly impact aggregate expenditure and the equilibrium level of real GDP. These changes affect consumption and net exports, which are key components of aggregate demand.

• Changes in Consumption:

  • Much of the private sector's wealth is held in assets with a fixed nominal value, such as money.

  • The real value of these assets depends on the price level; as prices rise, the purchasing power of money falls.

  • A rise in the price level lowers the real value of money, reducing autonomous desired consumption and shifting the aggregate expenditure (AE) function downward.

  • Conversely, a fall in the price level increases the real value of money, boosting consumption and shifting the AE function upward.

• Changes in Net Exports:

  • If the domestic price level rises (with an unchanged exchange rate), domestic goods become relatively more expensive compared to foreign goods.

  • Both domestic and foreign buyers reduce their purchases of Canadian-made goods and increase purchases of foreign goods.

  • This leads to a downward shift in the net exports (NX) and AE curves, decreasing equilibrium national income.

  • The reverse occurs if the domestic price level falls.

Changes in Equilibrium GDP

An exogenous increase in the price level causes the AE curve to shift downward, resulting in a lower equilibrium level of real GDP.

• Equilibrium Change: The equilibrium point moves from $E_0$ to $E_1$, and real GDP falls from $Y_0$ to $Y_1$.

• Graphical Representation: The AE curve shifts downward, and the new equilibrium is at a lower level of output.

• Equation: $AE = C + I + G + NX$ where $C$ is consumption, $I$ is investment, $G$ is government spending, and $NX$ is net exports.

The Aggregate Demand Curve

The aggregate demand (AD) curve illustrates the combinations of real GDP and the price level for which desired aggregate expenditure equals actual national income.

• Definition: The AD curve shows the relationship between the price level and the quantity of real GDP demanded.

• Movement Along the AD Curve: A rise in the price level shifts the AE curve downward, causing a movement upward and to the left along the AD curve (lower GDP). A fall in the price level shifts the AE curve upward, causing a movement downward and to the right along the AD curve (higher GDP).

• Key Formula: $AD: ext{Combinations of } (P, Y) ext{ where } AE = Y$

Example: Price Level and Aggregate Expenditure

Suppose the price level increases due to external factors. The real value of money held by consumers falls, leading to reduced consumption. Net exports also decline as domestic goods become less competitive. The AE curve shifts downward, and the equilibrium level of real GDP decreases.

Chapter Outline/Learning Objectives

Section	Learning Objectives
8.1 The Demand Side of the Economy	1. Explain why an exogenous change in the price level shifts the AE curve and changes the equilibrium level of real GDP. 2. Derive the aggregate demand (AD) curve and understand what causes it to shift.
8.2 The Supply Side of the Economy	3. Describe the aggregate supply (AS) curve and understand why it shifts when technology or factor prices change.
8.3 Macroeconomic Equilibrium	4. Explain how AD and AS shocks affect equilibrium real GDP and the price level.

Additional info: The notes above expand on the brief points in the slides, providing definitions, examples, and equations for key macroeconomic concepts relevant to the short-run relationship between real GDP and the price level.