Chapter 11 - Aggregate Demand I: Building the IS-LM Model Flashcards
What is related to the IS curve (2 things)? and the LM curve (1 thing)
IS curve: (investment and savings)
- Keynesian Cross
- LF model
LM curve: (Liquidity Dm, and M money supply)
- theory of liquidity preference
In model of AD-AS, what are 3 characteristics that vary in the LR and SR?
LR: flexible prices, output determined by production factors&tech, U rate = natural rate
SR: prices sticky, output determined by AD, U negatively related to output
What is the IS-LM model and its 3 assumptions?
the basis of the AD curve, when demand determines EQM (instead of supply)
Assumptions:
1. SR
2. Price level fixed (SRAS horizontal)
3. Closed economy (no NX)
3 steps to derive IS curve
Keynesian cross: interactions b/w I&Y
Investment function: interaction b/w I and r
Combine both interactions to get IS curve
What is the IS curve, what does each point on it represent?
plots different combo of interest rate and income level
each point is a level which G&S in EQM
Define Keynesian Cross?
How national income is determined by aggregate expenditures in SR
Define AE and PE
Actual Expenditure (AE): firm/households/gov actually spend on G&S
Planned Expenditure (PE): firm/household/gov would like to spend on G&S
what is the difference b/e AE and PE?
unplanned inventory investment
Define Unplanned inventory investment (UII). What does it signal?
changes in inventory (unplanned) which signals PE DNE AE
When is Keynesian Cross in EQM
when PE = AE
must be when UII = 0
What are equations for PE? (and what variables represent)
(1) PE = C + I + G
(2) PE = a+c(Y-Tbar) + Ibar + Gbar
- planned C expenditure (C): C = a + c(Y-T) - a - autonomous consumption - c = MPC (b/w 0-1, +) - planned inventory expenditure I = Ibar (endogenous) - Planned gov expenditures: G = Gbar - assume Y = AE = GDP real
(3) PE = (a + Ibar + Gbar – cTbar) + cy
- Vertical intercept: bracket portion
- Slope: c = changePE/changeY
What do PE and AE represent (in terms of markets)?
PE = demand
AE = supply
When does PE curve rise? What factors change?
up/down shifts PE curve due to intercept factors
Vertical intercept = a + Ibar + Gvar - cTbar
TF: changes in a, I, G, T impact PE curve (not c since c=MPC = slope
What is the EQM condition for the Keynesian Cross?
How do you graph it?
PE = Y (aka. D=S, PE = PS)
Graphing: 45% line through origin (since PE = Y at all points)
Given the PE curve and EQM condition lines, what are steps to find EQM income level (Y, x-axis)
Steps:
1. Draw both lines
2. Set Y = PE
3. Iscolate for Y
EQM level income equation:
Ye = 1/(1-c) * ( a+I+G-cT)
How do you reach EQM after shocks (general)
When shocks in PE occur, they cause unplanned inventory changes (negative relationship w PE change), and can be adjusted to EQM income through changes in production ( positive relationship w PE change)
results in new EQM Y (income) level and new PE level)
What causes and result from an increase in PE
caused by: increase a, I, G or decrease T
Result:
PE>Y1 (shortage)
unplanned inventory fall
increase production
Market EQM result: (Multiplier)
increased PE (supply)
increased Y (output, income)
What causes and results from an decrease in PE
caused by:
decrease a, I, G
increase T
Result:
PE>Y1 (surplus)
unplanned inventories rise
decrease production
Market EQ result (multiplier)
decrease PE (supply)
decrease Y (output, income)
After a shock and adjusting to EQM income, how do you measure the change in income (Y)
Multiplier (depends on c = MPC = slope of Y=PE)
change Y = ( 1/(1-c) ) * changeI or changeG or change factor (I, G)
tax multiplier is different
How do changes in tax impact the PE (demand), and production
- Tax negatively impact PE (since tax negatively impact C)
- If PE falls -> UII increase –> reduce output
If PE rises –> UII falls –> increase output - After change Y, move to new EQM
what is tax multiplier? What are 3 characteristics? How can you measure tax multiplier? How do you find associated change in Y (income)
tax multiplier:
change in income from $1 change in T
Characteristics:
1. Negative: since T negative relation with Y (through C)
2. Greater than 1 (abs. value): multiplier effect (exception: MPC=0.5, multiplier
3. Tax multiplier < spending multiplier
Multiplier:
changeY/changeT = -MPC/(1-MPC)
Change in income:
changeY = -MPC/(1-MPC)*changeT
Is tax multiplier or expenditure/spending multiplier more? Why?
Tax multiplier < spending multiplier
Reason: change in spending (G, I) spending has bigger impact than changeT
inital change in autonomous spending does not get saved in G spending expansion process, but does her saved in tax change process