Keynesian Liquidity Preference and Solow Growth Models

1. Keynes’ Liquidity Preference Theory and Interest Rates

According to Keynes’ Liquidity Preference Theory, what determines the overall level of interest rates in the short run? Based on that theory, what should a central bank do when it wants to lower interest rates? Explain.

The equilibrium condition is defined as: Ms/P = Ld (r* + πe, Y).

Basically, this implies that a central bank can reduce the real interest rate (r*) in the short run by increasing the money supply (Ms). To re-establish equilibrium, real money demand must increase, which requires the real interest rate to fall.

3. Stock Variables vs. Flow Variables in Macroeconomics

Describe the difference between stock variables and flow variables in macroeconomic models. Categorize the following: aggregate income, aggregate wealth, aggregate investment, the aggregate money supply, the government’s budget deficit, and the government’s debt.

• Flow variables: Measured over a specific period of time (e.g., aggregate income, aggregate investment, government budget deficit, government spending, consumption).
• Stock variables: Measured at a particular point in time (e.g., aggregate wealth, aggregate money supply, national debt).

For example, the budget deficit is a flow variable measured per year, whereas the national debt is a stock variable measured at any given moment.

9. Solow Growth Model: Break-Even Investment

In Solow’s model of economic growth, what is meant by “break-even investment”? How and why would an increase in the population growth rate affect the amount of investment (per person) needed to break even?

In the Solow growth model, break-even investment refers to the level of investment necessary to offset the effects of population growth and depreciation on the capital-labor ratio. Without sufficient investment, capital per worker would decline as the population grows and capital depreciates.

A higher rate of population growth implies a faster-expanding labor force. Consequently, the amount of capital required to maintain the same capital-labor ratio increases, necessitating a higher level of investment.