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1 Diploma Macro Paper 2 Monetary Macroeconomics Lecture 6 Aggregate supply and putting AD and AS together Mark Hayes.

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Presentation on theme: "1 Diploma Macro Paper 2 Monetary Macroeconomics Lecture 6 Aggregate supply and putting AD and AS together Mark Hayes."— Presentation transcript:

1 1 Diploma Macro Paper 2 Monetary Macroeconomics Lecture 6 Aggregate supply and putting AD and AS together Mark Hayes

2 Goods market KX and IS (Y, C, I) Money market (LM) (i, Y) IS-LM (i, Y, C, I) AD Labour market (P, Y) AS AD-AS (P, i, Y, C, I) Phillips Curve ( ,u) Foreign exchange market (NX, e) AD*-AS (P, e, Y, C, NX) Exogenous: M, G, T, i*, π e IS*-LM* (e, Y, C, NX) AD*

3 Goods market KX and IS (Y, C, I) Money market (LM) (i, Y) IS-LM (i, Y, C, I) AD Labour market (P, Y) AS AD-AS (P, i, Y, C, I) Phillips Curve ( ,u) Foreign exchange market (NX, e) AD*-AS (P, e, Y, C, NX) Exogenous: M, G, T, i*, π e IS*-LM* (e, Y, C, NX) AD*

4 4 Y1Y1 Y2Y2 Deriving the AD* curve Y  Y P IS* LM*(P 1 ) LM*(P 2 ) AD* P1P1 P2P2 Y2Y2 Y1Y1 22 11 Why AD* curve has negative slope: PP  LM shifts left      NX  Y Y  (M/P) (M/P)

5 5 Mundell-Fleming and the AD* curve  Previously P was fixed, now we are changing it.  NX is a function of , not e.  We now write the M-F equations as:  This means that the diagram does not show us the eq’m for e but we do not need this explicit for AD*

6 6 The effect of an increase in demand in the ‘short run’ and the ‘long run’ Y P AD 1 LRAS SRAS 1 P2P2 Y2Y2 A = initial (full employment) equilibrium A B C B = new short-run eq’m after a boom in confidence C = long-run equilibrium AD 2 SRAS 2 P1P1

7 7 Keynes’s original AD-AS model employment, N D expected income AS AD Equilibrium employment D*D* Effective demand

8 8 P Y LRAS AD SRAS A post-Keynesian AD-AS model in P, Y space Y

9 9 P Y LRAS AD PePe

10 10 Three models of aggregate supply 1.The imperfect-information model 2.The sticky-price model 3.The sticky-wage model All three models imply: natural rate of output a positive parameter the expected price level the actual price level agg. output

11 11 Three models of aggregate supply 1.The imperfect-information model 2.The sticky-price model 3.The sticky-wage model All three models imply: a positive parameter Deviations in price level from expectation Deviations in output

12 12 The imperfect-information model Assumptions:  All wages and prices are perfectly flexible, all markets clear  Each supplier produces one good, consumes many goods.  Supply of each good depends on its relative price: the nominal price of the good divided by the overall price level.

13 13 The imperfect-information model  All suppliers know the nominal price of the good they produce, but do not know the general price level.  Supplier does not know general price level at the time of the production decision, so uses the expected price level, P e.  Suppose P rises but P e does not.  Supplier thinks it is their own relative price which has risen, so produces more.  With many producers thinking this way, Y will rise whenever P rises above P e.

14 14 The sticky-price model  Assumption:  Firms set their own prices (monopolistic competition).  Reasons for sticky prices:  long-term contracts between firms and customers  menu costs  firms not wishing to annoy customers with frequent price changes

15 15 The sticky-price model  An individual firm’s desired price is where a > 0. Suppose two types of firms: firms with flexible prices, set prices as above firms with sticky prices, must set their price before they know how P and Y will turn out:

16 16 The sticky-price model  Assume sticky price firms expect that output will equal its natural rate. Then,  To derive the aggregate supply curve, we first find an expression for the overall price level.  Let s denote the fraction of firms with sticky prices. Then, we can write the overall price level as…

17 17 The sticky-price model price set by flexible price firms price set by sticky price firms

18 18 The sticky-wage model  Assumes that firms and workers negotiate contracts and fix the money wage before they know what the price level will turn out to be.  The money wage they set is the product of a target real wage and the expected price level: Target real wage

19 19

20 20 The sticky-wage model If it turns out that then Unemployment and output are at their natural rates. Real wage is less than its target, so firms hire more workers and output rises above its natural rate. Real wage exceeds its target, so firms hire fewer workers and output falls below its natural rate.

21 21 Chart 4.6 Real product wages, labour market slack and productivity Sources: ONS (including the Labour Force Survey) and Bank calculations. (a)Headline unemployment rate less the central Bank staff estimate of the medium-term equilibrium unemployment rate. For details, see the box on pages 28–29 of the August 2013 Report. (b)Private sector AWE total pay deflated by the market sector gross value added deflator. (c)Market sector output per worker.

22 22 Summary & implications Each of the three models of agg. supply imply the relationship summarized by the SRAS curve & equation. Y P LRAS SRAS

23 23 Summary & implications Suppose a positive AD shock moves output above its natural rate and P above the level people had expected. Y P LRAS SRAS 1 SRAS equation: AD 1 AD 2 Over time, P e rises, SRAS shifts up, and output returns to its natural rate. SRAS 2

24 24 Goods market KX and IS (Y, C, I) Money market (LM) (i, Y) IS-LM (i, Y, C, I) AD Labour market (P, Y) AS AD-AS (P, i, Y, C, I) Phillips Curve ( ,u) Foreign exchange market (NX, e) AD*-AS (P, e, Y, C, NX) Exogenous: M, G, T, i*, π e IS*-LM* (e, Y, C, NX) AD*

25 25 Inflation, Unemployment, and the Phillips Curve The Phillips curve states that  depends on  expected inflation,  e.  cyclical unemployment: the deviation of the actual rate of unemployment from the natural rate  supply shocks, (Greek letter “nu”). where  > 0 is an exogenous constant.

26 26 The Phillips Curve and SRAS  SRAS curve: Deviations in output are related to unexpected movements in the price level.  Phillips curve: Deviations in unemployment are related to unexpected movements in the inflation rate. SRAS Phillips curve

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30 30 Goods market KX and IS (Y, C, I) Money market (LM) (i, Y) IS-LM (i, Y, C, I) AD Labour market (P, Y) AS AD-AS (P, i, Y, C, I) Phillips Curve ( ,u) Foreign exchange market (NX, e) AD*-AS (P, e, Y, C, NX) Exogenous: M, G, T, i*, π e IS*-LM* (e, Y, C, NX) AD*

31 31 Next term  Policy effectiveness and inflation targeting  Origins of the North Atlantic and Euro crises


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