Week 3: Solow Growth Model Flashcards
Exogenous Variable
variable is given in model and is determined outside of the model
Endogenous Variable
variable that is determined by the model
Solow Growth Model
exogenous model of economic growth that analyses changes in the level of output in an economy over time
How is Solow Growth Model Different to Production Function? (3)
Augments production model with capital accumulation
Capital stock if no longer exogenous (variable given)
capital stock now endogenised (variable determined in model)
How do you set up the Solow Growth model?
Use old production function equation and add an equation for the accumulation of capital over time
Key aspects of the Solow Growth Model equation? (4)
- cobb douglas method
- constant returns to scale in capital and labour
- assume exponent of one third on capital
- all variable are time subscribed by t
What does a resource constraint assume?
Assumes no imports or exports and no gov spending
Resource Constraint Equation
C(t) + I(t) = Y(t)
C = consumption
I = investment
Capital Accumulation Equation
K(t+1) = K(t) + I(t) - dK(t) K(t+1) = next years capital K(t) = this years capital I(t) = this years investment d = depreciation rate
Capital Accumulation
an increase in assets from investments or profits
Change in Capital Stock Equation
△K(t=1) = K(t+1) - K(t)
Thus
△K(t=1) = I(t) - dK(t)
Is labour supply an endogenous variable in Solow Growth Model?
No for simplicity - amount of labour in economy is given exogenously at a constant level
L(t) = L
Consumption Equation in Solow Growth Model
I(t) = sY(t) I = investment s = fraction of total output invested
C(t) = (1-s)Y(t)
Saving Equation in the Solow Growth Model
Difference between income and consumption
Y(t) - C(t) = I(t) is saving Y(t) - C(t)
saving = investment
Two ways to solve Solow Growth model
- Graphical solution
2. Solve model in the long run
What happens at the rest point of the economy?
All endogenous variables are steady
In the steady state what is investment equal to?
investment = depreciation
Mathematical solution for the Steady State
Nul and void
What is the steady state level of capital positively related to? (3)
- investment rate
- size of the workforce
- productivity of the economy
What is the steady state level of capital negatively related to?
depreciation rate