The Multiplier - National Income

Summary

The multiplier effect in economics illustrates how initial changes in spending can lead to a larger overall increase in national income or GDP. It is influenced by factors such as the marginal propensity to consume, save, and import, as well as taxation and government spending.

• Multiplier — the ratio of the change in GDP to the initial change in spending. Example: A $20 billion increase in government spending leads to a$100 billion rise in GDP, resulting in a multiplier of 5.
• Marginal Propensity to Consume (MPC) — the proportion of additional income that is spent on consumption. Example: If a person receives an extra £100 and spends £70, the MPC is 0.7.
• Marginal Propensity to Save (MPS) — the proportion of additional income that is saved. Example: If the MPC is 0.7, then the MPS is 0.3.
• Marginal Rate of Tax (MRT) — the proportion of additional income that is paid in taxes. Example: If an extra income of $100 is taxed$20, the MRT is 0.2.
• Marginal Propensity to Import (MPM) — the proportion of additional income spent on imports. Example: If an extra income of $100 leads to$10 spent on imports, the MPM is 0.1.

Exam Tips

Key Definitions to Remember

• Multiplier
• Marginal Propensity to Consume (MPC)
• Marginal Propensity to Save (MPS)
• Marginal Rate of Tax (MRT)
• Marginal Propensity to Import (MPM)

Common Confusions

• Confusing the multiplier with the initial change in spending
• Misunderstanding the relationship between MPC, MPS, and the multiplier

Typical Exam Questions

• What is the multiplier effect? The multiplier effect is the process by which an initial change in spending leads to a larger overall change in GDP.
• How does a change in government spending affect national income? An increase in government spending can lead to a multiplied increase in national income, depending on the size of the multiplier.
• How do taxes affect the multiplier? Taxes reduce the multiplier effect by decreasing the amount of income available for further spending.

What Examiners Usually Test

• Understanding of how the multiplier works
• Ability to calculate the multiplier using given data
• Explanation of factors affecting the size of the multiplier