We have 5 basic macro-economic variables: Y,U,P,i, and e
Y is the bull's eye, which we try to control using fiscal and monetary policy
There are 4 stages to developing our economic model
1) Spendthrift (where there is just the firm and the household)
2) Frugal (which allows for spending and investment through banks)
3) Governed (which factors in taxation and government expenditure)
4) Open (which factors in imports and exports)
Our end-goal is to find the relationship between the general price level and the national income!
Here are some basic assumptions we have to make in building our macroeconomic model right now:
-Demand determines output
-The price level is constant (we pretend there is no inflation)
-In a basic economy, the interest and exchange rates remain constant
-We assume that potential national income is constant
Autonomous versus Induced Variables:
-Autonomous variables do not depend on national income, and thus are external to our model: this includes things like exports, which are determined by foreign economies, not domestic economies
Induced Variables DO depend on national income, and are thus found within our model: imports for an example tend to increase as Canada's national income grows, thus this an induced variable.
Today, we are going to learn about consumption, which is a very important part of national expenditure (the other parts being investment, government expenditure and net exports).
First: DESIRED versus ACTUAL EXPENDITURE:
-This is similar to microeconomics where we talked about willingness to buy (quantity demanded) at a given price. In Macro, we talk about the willingness to expend at a given income- it's a similar concept
-Actual aggregated expenditure is measured by NIEA (national income and expenditure accounts), which is denoted by an "a" subscript
-Desired expenditure is planned or intended expenditure
-It is a combination of consumption, investment, government expenditure, and net exports
-It is a function of national income (so national income effects expenditure)
THE CONSUMPTION FUNCTION: As a general rule, if people have more money, they spend more. Who'd have thunk...
-Consumption is a function of disposable national income! (Yd = current disposable income, which is national income minus taxes). However, in a spendthrift economy, we don't have to worry about taxation! =D
The ceteris paribus variable for the consumption function are
-Wealth (accumulated income: higher wealth generally leads to more consumption)
-Expectations (if prices are expected to rise in the future, this increases current consumption; if prices are expected to fall in the future, this decreases current consumption)
-Interest Rates (higher interest rates decreases consumption)
DESIRED CONSUMPTION IS A FUNCTION OF NATIONAL INCOME! John Meynard Keynes figured this out!
Here are some basic assumptions of the consumption function:
1) There is a break-even level of consumption (where consumption is exactly equal to disposable income)
2) as disposable income increases, consumption increases, but by less and less (in other words, the higher disposable income, the larger the portion of that income which will go into savings)
3) DESIRED CONSUMPTION IS A FUNCTION OF CURRENT DISPOSABLE INCOME!
*On a graph you can see this visually: consumption has risen with national income over the years in Canada.
Okay, so let's see one of these consumption functions!
-First off, this is a simplified version of the consumption function: most real ones would look more like curves, but we don't like to solve quadratics in this class
-The 45 degree line is where consumption is equal to disposable income- any point on this line is the break even point!
-As Y increases, so does C
-Here, Y = Yd (because this is a frugal economy)
-The slope of the consumption like is denoted by the variable 'b', and the actual term for it is the Marginal Propensity to Consume (MPC)
-The Y intercept is autonomous/exogenous expenditure which occurs even when there is no income: this is denoted by the variable 'a'
-Desired Consumption is 'C'
-Any point where consumption is higher than income has dissavings, or borrowed money, while any point where income is higher than consumption has savings
C = a + b(Yd)
for example: Consumption = 100 + 9/10(Disposable Income)
Basically
-Income is either spend (so it goes into consumption) or not spent (so it goes into savings)
-Savings are non-consumption
-Disposable income is then equal to consumption + savings
-Negative savings are dissavings, or loans
-Savings are Disposable income minus consumption
-At the break even point, income is equal to consumption, and savings is equal to zero
It is possible to build a savings function from the consumption function!
The savings function is derived from C = a + b(Yd)
S = Yd - C
if C is a straight linear function, then...
S = -a + (1-b)Yd
S = the vertical distance between C and the break even line (45 degrees)
SOME OTHER TERMS WHICH ARE IMPORTANT TO REMEMBER:
Average Propensity to Consume (APC): This is consumption divided by disposable income- this is the slope of the ray from the origin to the point being considered
Marginal Propensity to Consume (MPC): This is a change in consumption divided by a change in disposable income- this is the slope of the tangent to the curve being considered (so, for this very simplified, linear graph, it is equal to the slope of the consumption function)
Average Propensity to Save (APS): This is savings divided by disposable income- this is the slope of the ray from the origin to the point being considered on the savings function
Marginal Propensity to Save (MPS): This is a change in savings divided by a change in disposable income- this is the slope of the tangent to the curve being considered on the savings function (so for this linear savings curve, it's just equal to the slope of the savings function)
SOME MATHEMATICAL RELATIONSHIPS WHICH WILL MAKE PERFECT SENSE
Income = Consumption + Savings
Income/Income = Consumption/Income + Savings/Income, so 1 = APC + APS
/\Income//\Income = /\Consumption//\Income + /\Savings//\Income, so 1 = MPC + MPS
MPC is a value between 0 and 1
C = a + b(Yd) where a = the vertical intercept and b = MPC
THAT'S ALL FOR TODAY
No comments:
Post a Comment