IS-LM Model and Fiscal/Monetary Policy Part B

Assessing Fiscal and Monetary Policy through the IS-LM Model

IS-LM Model Overview

• The IS-LM model assesses the impact of fiscal and monetary policies on output and interest rates.
• It's based on the intersection of the IS (Investment-Savings) curve and the LM (Liquidity Preference-Money Supply) curve.

IS and LM Curves

• IS Curve:
  • Represents equilibrium in the goods market.
  • $Y = C(Y - T) + I(Y,i) + G$
    • Where:
      • $Y$ = Output
      • $C$ = Consumption, which is a function of disposable income ($Y - T$)
      • $T$ = Taxes
      • $I$ = Investment, which is a function of output ($Y$) and interest rate ($i$)
      • $G$ = Government spending
  • An increase in the interest rate leads to a decrease in output, resulting in a downward-sloping IS curve.
• LM Curve:
  • Represents equilibrium in financial markets.
  • $M/P = YL(i)$
    • Where:
      • $M$ = Money supply
      • $P$ = Price level
      • $Y$ = Output
      • $L(i)$ = Liquidity preference (money demand), which is a function of the interest rate ($i$)
  • An increase in output leads to an increase in the interest rate, resulting in an upward-sloping LM curve.
• Equilibrium:
  • The intersection of the IS and LM curves (point A) indicates the point at which both goods and financial markets are in equilibrium.

Fiscal Policy

• Fiscal policy involves government decisions related to spending and taxation.
• Fiscal Contraction (or Fiscal Consolidation):
  • A policy aimed at reducing the budget deficit.
  • Example: Increasing taxes while holding government spending constant.
  • Impact: Shifts the IS curve to the left (from IS to IS').
  • Effects: lowers both interest rate ($i$) and output ($Y$) from A to A'
• Fiscal Expansion:
  • An increase in the budget deficit.
• Taxes and the IS Curve:
  • Changes in taxes primarily affect the IS curve, not the LM curve.

Monetary Policy

• Monetary policy involves actions taken by the central bank (e.g., ECB) to influence the money supply and interest rates.
• Monetary Expansion:
  • An increase in the money supply, often implemented through open market operations.
  • Impact: Shifts the LM curve down (from LM to LM').
  • Effects: lowers the interest rate ($i$) and raises output ($Y$) from A to A'
• Monetary Contraction (or Monetary Tightening):
  • A decrease in the money supply.
• Money Supply and the LM Curve:
  • Changes in the money supply primarily affect the LM curve, not the IS curve.

IS-LM Equilibrium and Policy Effects

• Fiscal Contraction Example:
  • Initial Equilibrium: Point A, defined by interest rate ($i$) and output ($Y$).
  • After Tax Increase: IS curve shifts left to IS'. Disequilibrium occurs at the initial interest rate (Point D).
  • New Equilibrium: Point A', with lower interest rate ($i'$) and lower output ($Y'$).
• Monetary Expansion Example:
  • Initial Equilibrium: Point A, defined by interest rate ($i$) and output ($Y$).
  • After Increase in Money Supply: LM curve shifts down to LM'. Disequilibrium occurs at the initial output level (Point B).
  • New Equilibrium: Point A', with decreased interest rate ($i'$) and increased output ($Y'$).

Liquidity Trap

• Definition:
  • A situation where the interest rate is at or near zero, and people are indifferent between holding money and bonds.
  • Money demand becomes horizontal.
• Implications:
  • Further increases in the money supply have no effect on the interest rate.
  • The LM curve has a flat segment when the interest rate is zero, becoming upward sloping at higher output levels.
• IS-LM Model in a Liquidity Trap:
  • Monetary policy becomes ineffective in stimulating output.
  • There's a limit to how much monetary policy can increase output, potentially preventing it from returning to its natural level.

Policy Mix

• Definition:
  • The combination of monetary and fiscal policies used to achieve macroeconomic goals.
• Application:
  • Policies can be used in the same direction (e.g., fiscal expansion and monetary expansion) or in opposite directions (e.g., fiscal contraction and monetary expansion).

Effects of Fiscal and Monetary Policy (Table Summary)