Day 3: Solow (done) Flashcards
What’s the theory of capital accumulation in the Solow model?
Capital accumulation is endogenized in the Solow model (turned from exogenous into endogenous variable)
- Solow model allows us to consider capital accumulation as a possible factor of long-run economic growth
What’s econ. growth?
an increase in output/GDP (Y)
Determinants of production?
Capital: machines, factories, roads, etc.
Labor: number of people working
Technology
What’re stock variables?
A quantity that survives from period to period
Eg. tractor, house, factory, wealth, government debt (a debt that persists over time unless paid off).
What’re flow variables?
A quantity that lasts a single period. Time frame/period matters, need it to make sense
The change in a stock is a flow: the change in the capital stock, for example, is the flow of investment.
Eg. savings/investments (quarter, year), meals consumed, withdrawal from ATM
In solow model, what’re the stock variables?
capital and labor
What’s the real interest rate?
Nominal interest rate - inflation
It’s real bc it’s measured in units of output/constant dollars rather than nominal dollars.
What’s savings?
the difference between income and consumption
Y-C = Inv/savings
What’s a production function?
a production function shows how much output/GDP (Y) can be produced given 2 inputs, which are EXOGENOUS variables
What’s the production function for the Solow model?
- 2 Inputs/exogenous variables are the factors of production: capital K and labor L
- Output/endogenous variable: GDP
- Y = F(K,L) = AK^1/3L2/3
- A’s constant
What’re the properties of the production function for the Solow model?
- displays constant returns to scale with 2 exogenous inputs ( labor, capital)
- decreasing returns to scale/marginal returns by increasing 1 input while keeping other constant (increasing K but not L leads to decreasing marginal returns)
What’re constant returns to scale?
constant returns to scale are when an increase in inputs (capital and labour) cause the same proportional increase in output.
Ex.: if you double inputs, you double outputs
Effect of constant RTS on solow growth production function?
This makes the growth model “scale-free”
Meaning returns aren’t affected depending on the specific scale/size of individuals you’re examining
In solow model, what can you do with the final output?
Can either consume or invest (in capital) the final output
Consumption + Investment = Y
Formulas for Consumption?
- C = (Y - I) = (1-s)Y = (1-s)(AK^⅓ L^⅔)
2. per capita consumption C/L = (1-s)AK^⅓ L^-⅓.
What’s a closed economy (solow)?
no imports/exports
What’s a resource constraint in solow ?
Tells you how much you’re consuming/investing.
A constraint on how the economy can use its resources
What’s held constant in solow model?
WORK IN PROGRESS!!!!!!!
- Labor (no population growth)
What’s “s” in the solow model?
S is the savings/investment rate, the fraction of GDP that’s invested in capital
What’s investment in the solow model?
Investment’s a constant fraction of output GDP
I = sY
IMPORTANT: What’s the relationship between growth and investment?
GROWTH causes investment, not the other way around.
What’s consumption in the solow model?
consumption’s is the difference between output and investment.
- C = (1-s)Y
- C = Y - I
How to calculate the change in a variable in 2 periods?
- Divide C(new)/C(old) 2nd formulas for the proportion of new to old
- Then use the percent change formula
Is consumption affected by depreciation?
No! consumption’s is the difference between output and investment.
- C = Y - I
What’s consumption in the solow long-run?
In the long-run consumption’s constant. With transition dynamics, consumption will increase below SS, decrease above SS to reach the steady state.
What happens to consumption as capital K increases and you move along horizontal axis?
consumption always INCREASES as K increases!
What’s the formula for capital accumulation? (moving right along solow)
Next year’s capital is the sum of this year’s capital and the net investment/change in capital.
K(t+1) = K(t) + (I - dK)
What does the capital accumulation formula tell you for solow?
Capital accumulation tells you by how much next period’s amount of capital will increase, by how much you’re investing
What’s the depreciation rate?
The amount of capital that wears out each period
How does depreciation rate work?
Mathematically must be between 0 and 1 for solow.
0: no wear and tear on capital
1: you lose all of your capital
What’s the depreciation rate often?
Often viewed as approximately 10%
What’s A?
- A is the level of total factor productivity (TFP)/technology/productivity parameter
How does productivity affect the solow production function and solow model?
Productivity influences output in both the production function and solow model, but explains a larger difference in the Solow model, bc it also affects the accumulation of capital there.
What’s the net investment or net change in capital?
how much capital/x-axis changes in the next time period, investment minus depreciation
net investment/cc = sY (investment) - dK (depreciation)
How come we always reach the steady state in solow as you increase investment?
- because investment gives you DIMINISHING returns!
As you increase investment by a constant amount, you get diminishing returns on investment, but depreciation increases by a constant amount.
= by adding more capital, depreciation increases at a higher rate than your investment.
What’s the steady state?
- where investment equals depreciation
- Capital K is constant in the long-run here, as investment is just enough to cover depreciation, none left over to invest in more capital stock.
What’re the parameters in the solow model?
these are given and unless shocked, stay constant
- A, s, d, L, K0
What’re the exogenous variables in solow?
All starting point variables (Capital K0, Y0, L0, C0, and I0)