Real Intertemporal Model With Investment Flashcards
What is the consumers budget constant in the real inter temporal model?
c = w(h-l) + π - T - s
What is the effect of an increase in savings on the consumers budget constant in the full inter temporal model?
- ↓C
- ↓l → Ns↑
What effect does the interest rate have on labour supply?
- An increase in r increases current labour supply
- Inter temporal substitution of leisure
- Increases labour so can save more and consume more in future (takes advantage of the fall in price)
What is the current price of leisure relative to the future price?
- (w(1+r))/w’
- Therefore an increase in r given w and w’ results in in increase in the price of current leisure relative to future leisure
How does we affect labour supply?
- Current leisure decreases when lifetime wealth increases
- C,C’,L,L’ are all normal goods
What is MPC?
Slope of consumption demand vs current income: Marginal propensity to consume
How does r affect consumption demand?
- ↑r → ↑s = ↓c
What affect does we have on consumption demand?
- ↑we → ↑c
- As c is normal
What is future capital for the firm in the full model?
K’ = (1-d)K + I
What are the firms’ two profit equations in the full model?
- π = Y - wND - I
- 2. π’ = Y - w’N’D + (1-d)K’
What is V and what does this represent?
- V = π + π’/(1+r)
- Present value of profit
- Firm tries to maximise this by choosing N, N’ and I
What is the firms labour decision when I > 0
πgross = π + I = Y - wND
What is true of investments and dividends in the full model?
Increases in investment must be met by reduced dividend payments
What is MC(I)?
- Marginal Cost of investment = 1
- MC(I) for the firm is what it gives up, in terms of the present value of profits V, by investing in one unit of capital in the current period.
- This works out to be 1
What is MB(I)?
- Marginal benefit of investment: (MPK’ + (1-d))/(1+r)
- What one extra I in current period adds to the present value of profits V
What is the firms optimal investment rule?
- MPK’ - d = r
- Net Marginal product of capital = the real interest rate
- Determines a negative relationship between K’ and r: if r↑ then the firm will choose a smaller K’ so as to increase MPK’
What is the optimal investment schedule?
- The firm’s net marginal product of capital as a function of
investment given the initial quantity of capital K - relationship between r and I
- Line called MPK’ - d
What are the determinants of investment?
- r
- d
- ↑d → ↑I
- Must offset with more I
- Anything that effects MPK’
How does z’ affect investment in the full model?
- z’
- ↑z’ → ↑I
- If z is expected to be higher in the future we would invest more
How does K affect investment in the full model?
- K
- ↓K → ↑I
- b/c ↓K → ↑MPK’
How does N affect investment in the full model?
- N
- ↑N → ↑I
- b/c ↑N → ↑MPK’
How do credit market frictions affect the firms investment decision in the full model?
- Bad firms vs good firms - asymmetric information: rloan - rlending = x, default premium, interest rate spread
- x would increase during crisis
- For firms that borrow to invest, MPK’ - x - d = r