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    Structural VAR and Applications

    Jean-Paul Renne

    Banque de France

    ENSTA, 22 January 2010

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 1 / 55

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    Overview of the presentation

    1 Vector Auto-Regressions

    DefinitionEstimationTests

    2 Impulse responsesGeneral conceptApplication to Structural VAR

    3 Applications

    1 Blanchard and Quah (1989)2 Smets and Tsatsaronis (1997)3 Dedola and Lippi (2005)

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    Structural VARVector Auto-Regressions: Short introduction

    The VAR are widely used in economic analysis.

    While simple and easy to estimate, they make it possible toconveniently capture the dynamics of multivariate systems.

    VAR popularity is mainly due to Sims (1980) influential work.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 3 / 55

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    Structural VARVector Auto-Regressions: Notations

    let yt denote an (n 1) vector of random variables. yt follows a pth

    order Gaussian VAR if, for all t, we have

    yt = c + 1yt1 + . . .pytp + t

    where t N(0,).

    Consequentlyyt | yt1,yt2, . . . ,yp+1 N(c +1yt1 + . . .pytp,).

    Denoting with the matrix

    c 1 2 . . . p

    and with xt the

    vector 1 yt1 yt2 . . . ytp , the log-likelihood is given byL(YT; ) = (Tn/2) log(2) + (T/2) log

    1

    1

    2

    T

    t=1 yt

    xt

    1

    yt

    xt

    .

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 4 / 55

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    Structural VARVector Auto-Regressions: Maximum Likelihood Estimation (MLE)

    The MLE of, denoted with is given by

    = Tt=1

    ytx

    t T

    t=1xtx

    t1

    . (1)

    Exercise 1

    After having computed the jth rows of , find an easy way to

    estimate .

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 5 / 55

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    Structural VARVector Auto-Regressions: Maximum Likelihood Estimation (MLE)

    Proof of equation (1)Lets rewrite the last term of the log-likelihood

    T

    t=1yt

    xt

    1

    yt xt =

    Tt=1

    yt

    xt + xt

    xt

    1yt

    xt + xt

    xt

    =

    Tt=1

    t + (

    )

    xt1

    t + (

    )

    xt

    where the jth element of the (n 1) vector t is the sample residual forobservation t from an OLS regression of yjt on xt.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 6 / 55

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    Structural VARVector Auto-Regressions: Maximum Likelihood Estimation (MLE)

    T

    t=1yt

    xt

    1

    yt xt =

    Tt=1

    t1t + 2

    Tt=1

    t1( )xt

    +

    Tt=1

    x

    t( )1

    ( )

    xt

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 7 / 55

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    Structural VARVector Auto-Regressions: Maximum Likelihood Estimation (MLE)

    Lets apply the trace operator on the second term (that is a scalar):

    T

    t=1

    t1( )xt = trace

    T

    t=1

    t1( )xt

    = trace

    Tt=1

    1( )xtt

    = trace1

    ( )

    Tt=1

    xt

    t

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 8 / 55

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    Structural VARVector Auto-Regressions: Maximum Likelihood Estimation (MLE)

    Given that, by construction, the sample residuals are orthogonal to theexplanatory variables, this term is equal to zero.If xt = ( )

    xt, we have

    Tt=1

    yt

    xt

    1yt

    xt

    =

    T

    t=1

    t1t +

    T

    t=1

    xt1xt

    Since is a positive definite matrix, 1 is as well. Consequently, thesmallest value that the last term can take is obtained when xt = 0,ie when

    = .

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 9 / 55

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    Structural VARVector Auto-Regressions: Maximum Likelihood Estimation (MLE)

    Assume that we have computed , the MLE of is the matrix that

    maximizes L(YT; ,).

    Denoting with t the estimated residual yt xt, we have

    L(YT; ,) = (Tn/2) log(2) + (T/2) log 1

    12

    Tt=1

    t

    1t

    .

    is a symmetric positive definite matrix. Fortunately, it turns out

    that that the unrestricted matrix that maximizes the latter expressionis a symmetric postive definite matrix. Indeed,

    ()

    =

    T

    2

    1

    2

    T

    t=1t

    t = =

    1

    T

    T

    t=1t

    t.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 10 / 55

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    Structural VARVector Auto-Regressions: Likelihood-Ratio test

    The simplicity of the VAR framework and the tractability of its MLEcontribute to convenience of various econometric tests. We illustratethis here with the likelihhod ratio test.

    The maximum value achieved by the MLE is

    L(YT; ,) = (Tn/2) log(2) + (T/2) log1

    1

    2

    Tt=1

    t1

    t

    .

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 11 / 55

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    Structural VARVector Auto-Regressions: Likelihood-Ratio test

    The last term isTt=1

    t1t = trace

    Tt=1

    t1t

    = trace Tt=1

    1tt

    = trace1

    Tt=1

    tt

    = trace1

    T

    = Tn.

    Therefore

    L(YT; ,) = (Tn/2) log(2) + (T/2) log1 Tn/2.

    which is easy to calculate.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 12 / 55

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    Structural VARVector Auto-Regressions: Likelihood-Ratio test

    For instance, assume that we want to test the null hypothesis that aset of variable follows a VAR(p0) against the alternative specificationof p1 lags (with p1 > p0).

    Let us respectively denote with L0 and L1 the maximum log-likelihoodsobtained withp0 and p1 lags. Under the null hypothesis, we have

    2

    L1 L0

    = T

    log11

    log

    10

    which asymptotically has a 2

    distribution with degrees of freedomequal to the number of restrictions imposed under H0 (compared withH1), ie n

    2(p1 p0).

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 13 / 55

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    Structural VARVector Auto-Regressions: Unconditional variance

    The unconditional matrix of variance-covariance of yt is

    Var(y) = limt

    E0((yt yt)(yt yt))

    where yt denotes the unconditional mean of y.

    Let denote with yt the vector

    yt y

    t1 . . . y

    tp

    , we have

    y

    t =

    c0

    ...0

    +

    1 2 p1 0 0

    0 . . . 0 00 0 1 0

    yt1 +

    t0

    ...0

    yt = c + yt1 +

    t

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 14 / 55

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    Structural VARVector Auto-Regressions: Unconditional variance

    It is then easy to get the Wolds decomposition of yt :

    yt = c + c + yt2 + t1+ t

    = c + t +(c + t1) + . . . +

    k(c + tk) + . . .

    The ts being iid, we have

    Var(y) = +

    + . . . + k

    k + . . .

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 15 / 55

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    Structural VARVector Auto-Regressions: Criteria

    In a VAR, adding lags quickly consume degrees of freedom. If laglength is p, each of the n equations contains n p coefficients plusthe intercept term.

    Adding lengths improve in-sample fit, but is likely to result inover-parameterization and affect the out-of-sample prediction

    performance.To select appropriate lag length, some criteria can be used (they haveto be minimized)

    AIC = log

    +

    2

    TN

    SBIC = log+ log T

    TN

    where N = n p2 + p.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 16 / 55

    S l V

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    Structural VARVector Auto-Regressions: Granger Causality

    Granger (1969) developed a method to analyze the causal relationshipamong variables systematically.

    The approach consists in determining whether the past values of y1,tcan help to explain the current y2,t.

    Let us denote three information sets

    I1,t = {y1,t,y1,t1, . . .}

    I2,t = {y2,t,y2,t1, . . .}

    It = {y1,t,y1,t1, . . .y2,t,y2,t1, . . .} .

    We say that y1,t Granger-causes y2,t if

    E [y2,t | I2,t1] = E [y2,t | It1] .

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 17 / 55

    S l VAR

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    Structural VARVector Auto-Regressions: Unconditional variance

    To get the intuition behind the testing procedure, consider thefollowing bivariate VAR(p) process:

    y1,t = 10 + pi=111(i)y1,ti +

    pi=112(i)y2,ti + u1,t

    y2,t = 20 + pi=121(i)y1,ti +

    pi=122(i)y2,ti + u2,t.

    Then,y1,t does not Granger-cause y2,t if

    21(1) = 21(2) = . . . = 21(p) = 0.

    Therefore the hypothesis testing isH0 : 21(1) = 21(2) = . . . = 21(p) = 0

    HA : 21(1) = 0 or 21(1) = 0 or . . .21(p) = 0.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 18 / 55

    S l VAR

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    Structural VARVector Auto-Regressions: Unconditional variance

    Rejection of H0 implies that some of the coefficients on the laggedy1,ts are statistically significant.

    This can be tested using the F-test or asymptotic chi-square test.The F-statistic is F = (RSSUSS)/p

    USS/(T2p1) (where RSS: restricted residual

    sum of squares, USS: unrestriced residual sum of squares)Under H0, the F-statistic is distributed as F(p, T 2p 1)In addition, pF 2(p).

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 19 / 55

    St t l VAR

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    Structural VARVector Auto-Regressions: Impulse responses

    Objective: analyzing the effect of a given shock on the endogenousvariables.

    Let us consider a random variable yt that presents the followingWolds decomposition:

    yt =k=0

    ktk.

    The impulse response function of the shock t on yt,yt+1, . . . is givenby the matrices

    k.

    Formally, the impulse response of the shock t on the variable y isdefined as

    yt+kt

    = k.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 20 / 55

    St t l VAR

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    Structural VARVector Auto-Regressions: Impulse responses

    Dynamics of yt,yt+1,yt+2, . . . when t = 1, t+1 = 0, t+2 = 0, . . .

    ! !

    !!

    !"

    !#

    "#

    "#$%

    "#$&

    "#$'

    "#$(

    "#$)

    "#$*

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 21 / 55

    St ct al VAR

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    Structural VARVector Auto-Regressions: Impulse responses

    Exercise 2

    Consider the process

    yt = 1 + 0.9yt1 + t.

    Compute the unconditional mean and variance of yt.

    Exercise 2

    Consider the process

    yt = 1 + 0.5yt1 + 0.4yt2 + t.

    Draw the impulse response of yt to t (up to yt+3). What is thecumulated impact of a shock (t = 1, t+1 = 0, t+2 = 0, . . .) onyt?

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 22 / 55

    Structural VAR

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    Structural VARVector Auto-Regressions: Causal mechanisms

    Assume that the GDP growth gt is affected by some real shocks ur,tfollowing

    gt = 0.3(it1 t) + ur,t

    where it denotes the nominal interest rate and t denotes the inflationrate.

    Besides, assume that we have

    it = 0.9it1 + 1.5t + ump,t

    t = 0.9t1 + 0.2gt1 + un,t

    where ump,t and un,t are respectively some monetary-policy andcost-push shocks.

    The strucural shocks ut are uncorrelated (i.e., the covariance matrix ofut, denoted with u is diagonal) and ut is serially uncorrelated (i.e.Cov(utk, ut) = 0 for any t and k > 0).

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 23 / 55

    Structural VAR

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    Structural VARVector Auto-Regressions: Causal mechanisms

    The structural model reads

    gt = 0.3(it1 t) + ur,t

    it = 0.9it1 + 1.5t + ump,t

    t = 0.9t1 + 0.2gt1 + un,

    t.

    To get it in a reduced-form, let us substitute t in the right-handsides of the first two equations:

    gt = 0.06gt1 0.3it1 + 0.27t1 + 0.3un,

    t + ur,

    t

    it = 0.9it1 + 1.35t1 + 0.3gt1 + ump,t + 1.5un,t

    t = 0.9t1 + 0.2gt1 + un,t.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 24 / 55

    Structural VAR

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    Structural VARVector Auto-Regressions: Causal mechanisms

    Exercise 3

    Write the model in matrix form.

    Is this economy stationary?

    Propose a way of estimating the model.

    How to recover the structural shocks ut?

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    Structural VAR

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    Structural VARVector Auto-Regressions:Impulse responses

    In matrix form

    gtitt

    =

    0.06 0.3 0.270.3 0.9 1.350.2 0 0.9

    gt1it1t1

    +

    g,ti,t,t

    with

    g,ti,t

    ,t

    =

    1 0 0.30 1 1.5

    0 0 1

    ur,tump,t

    un,t

    = B

    ur,tump,t

    un,t

    .

    With the procedure described above, one only gets an estimate of

    where

    = Var

    g,ti,t

    ,t

    .

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 26 / 55

    Structural VAR

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    Structural VARVector Auto-Regressions:Impulse responses

    Note however that we must have

    = BuB

    where u is diagonal positive.

    In addition, given the structural framework, one knows that B is anupper-triangular matrix.

    The Choleshy decomposition can therefore be used to get the Bmatrix.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 27 / 55

    Structural VAR

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    Structural VARVector Auto-Regressions:Impulse responses

    Whereas the VAR model is able to capture efficiently the interactionsbetween the different variables, it does not allow to reveal theunderlying causal mecanisms since two different causal schemes cancorrespond to the same reduced forms.

    By taking into account certain economic relationships, a StructuralVAR model (SVAR) makes it possible to identify structural shockswhile letting play the interactions between the different variables (seeGali, 1992 or Gerlach and Smets 1995).

    Formally, let assume that the residuals t are some linear combinations

    of the structural shocks ut, that is:

    t = But.

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    Structural VAR

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    Structural VARVector Auto-Regressions:Impulse responses

    How it has been shown previously, a SVAR is based on a structuralmodel that draws from a theoretical framework.

    As a starting point, we always have = BuB that provides us with

    n(n + 1)/2 restrictions to recover the B matrix.

    Consequently, to get the B matrix, one have to impose n(n 1)/2additional restrictions.

    There exist two kinds of restrictions that can be easily implemented ina SVAR: short-run and long-run restrictions:

    a short-run restriction prevents a structural shock from affecting anendogenous variable contemporaneously;a long-run restriction prevents a structural shock from affecting anendogenous variable in a cumulative way.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 29 / 55

    Structural VAR

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    Structural VARVector Auto-Regressions:Impulse responses

    Concretely, the short-run restrictions consists in setting to zero some

    entries of B.

    The long-run restrictions require additional computations to beapplied. More precisely, one needs to implement the computation ofthe cumulative effect of one of the structural shocks ut on one of the

    endogenous variable.Assume that we have the (reduced-form) VAR

    yt = c +1yt1 + . . .pytp + t.

    As was shown previously, one can always write a VAR(p) as a VAR(1),by stacking yt,yt1, . . .ytp+1 in a vector y

    t . Consequently, let usconsider only the VAR(1) case:

    yt = c + yt1 + t.

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    Structural VAR

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    Structural VARVector Auto-Regressions:Impulse responses

    Once more, let us consider the Wolds form of yt:

    yt = c + t + (c + t1) + . . . + k (c + tk) + . . .

    = c + But + (c + But1) + . . . + k (c + Butk) + . . .

    Consequently, the cumulated effect of the first structural shock u1,t onthe endogenous variables is obtained by computing

    (B +

    B + . . . +k

    B + . . .)

    0

    ...0

    if the initial shock of u1,t is of magnitude .

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    Structural VAR

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    Vector Auto-Regressions:Impulse responses

    In this context, consider the following long-run restriction: the jth

    structural shock does not affect,in a cumulative way, the ith

    endogenous variable.

    Then, denoting with the matrix (I ++ . . . +k + . . .)B, it comesthat the entry (i,j) of must be equal to zero.

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    Structural VAR

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    A simple SVAR

    It can be noted that short-run restrictions are simpler to implementthan long-run one.

    There are particular cases in which some well-known matrixdecompostion can be used to easily estimate some specific SVAR.

    Imagine a context in which you can argue that there exists an

    ordering of the shocks:A first shock (say, 1,t) can affect instantaneously (i.e., in t) only oneof the endogenous variable (say, y1,t);A second shock (say, 2,t) can affect instantaneously (i.e., in t) thefirst two endogenous variables (say, y1,t and y2,t);

    ...

    Exercise 4

    In such a context, what is the form of the matrix B?

    Suggest a methodology to estimate such a SVAR.

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    Structural VAR

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    Cholesky decomposition: Illustration

    Dedola and Lippi (The Monetary Transmission Mechanism: Evidencefrom the Industries of Five OECD Countries, 2005) estimate 5structural VAR for the US, the UK, Germany, France and Italy toanalyse the monetary-policy transmission mechanisms.

    They estimate an SVAR over the period 1975-1997, using 5 lags in

    VAR.

    The shock-identification scheme is based on Cholesky decompositions,the ordering of the endogenous variables being: the industrialproduction, the consumer price index, a commodity price index, the

    short-term rate, a monetary aggregate and (except for the US).This ordering implies that monetary policy reacts to the shocksaffecting the first three variables but that the latter react to monetarypolicy with a one-period lag.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 34 / 55

    Structural VAR

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    Responses of Macro-variables to a monetary policy shock

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    Structural VAR

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    Responses of Macro-variables to a monetary policy shock

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    Illustration: Blanchard and Quah (1989)

    The article The Dynamics Effects of Aggregate Demand and SupplyDisturbances (AER, 1989) implements long-run restrictions in asmall-sized VAR.

    Two variables are considered GDP and unemployment.

    Consequently, the VAR is affected by two types of shocks.

    The authors want to identify supply shocks (that xan have apermanent effect on output) and demand shocks (that can not have a

    permanent effect on output).

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    Illustration: Blanchard and Quah (1989)

    The motivation of the authors regarding their long-run restrictions can

    be obtained from a traditional Keynesian view of fluctuations.The authors propose a variant of a model from Stanly and Fisher(1977)

    Yt = Mt Pt + a.t (2)

    Yt = Nt + t (3)

    Pt = Wt t (4)

    Wt = W |

    Et1Nt = N

    (5)

    To close the model, the aithors assume the following dynamics for themoney supply and the productivity

    Mt = Mt1 + dt

    t = t1 + st

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    Illustration: Blanchard and Quah (1989)

    In this context, it can be shown that

    gnpt = dt

    dt1 + a.(

    st

    st1) +

    st

    ut = dt a

    st

    Then, it appears that the demand shocks have no long-run impact onoutput. Besides, neither shocks have a long-run impact onunemployment.

    The endogenous variable is ( gnpt ut) where gdpt denotes thelogarithm of GNP.

    It is assumed to be stationary. Therefore, neither disturbances has along-run effect on unemployment or the rate of change in output.

    The long-run restriction implies that the demand shocks also have nolong-run effect on the output level gnp itself.

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    Illustration: Blanchard and Quah (1989)

    Estimation data: quarterly, from 1950:2 to 1987:4.8 lags.

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    Dynamic effects of demand disturbancesHE AMERICAN ECONOMIC REVIEW SEPTEMBER 1989

    positions onlymic effects ofces.d and Supply

    and and sup-in Figures 1gures 1 and 2of output andthe horizontal. Figures 3-6but now withs around thehump-shaped

    oyment. Their

    1.401.201.00-0.80 --0.60-0.400.200.00 ,,,

    -0.20 0 10 20 30 40-0.40-0.60 -

    FIGURE 1. RESPONSE TO DEMAND,-= OUTPUT,- = UNEMPLOYMENT

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 41 / 55

    Structural VAR

    but now withs around the

    - . -FIGURE 1. RESPONSE TO DEMAND,-= OUTPUT,

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    Dynamic effects of supply disturbanceshump-shapedoyment. Theirquarters. Theine to vanishThe responsesare mirror im-to this aspectussing the ef-llest when thellowing for anemploymentcays the mostchange in theis allowed, thehanges in un-ively unimpor-mand distur-onsistent withmic effects of

    - = UNEMPLOYMENT

    1.000.800.60 -/0.40-0.20 -0.00 l+q ii i0 10 20 3 0 40-0.20 -

    -0.40-0.60-

    FIGURE 2. RESPONSE TO SUPPLY, OUTPUT,- = UNEMPLOYMENT

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 42 / 55

    Structural VARV A R i I l

    In the interveningnd output devia- 7.607.40

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    Vector Auto-Regressions:Impulse responses

    Uutput-gap deifnition

    The output gap is the component of GNP that is explained only by demandshocks.

    . At the peak re-s an implied coef-four, higher in ab-coefficient. Thatoefficient is higherthan for demandat we expect. Sup-to affect the rela-employment, andtle or no change in

    sof Demand andbances.mic effects of eachext step is to assessto fluctuations innt. We do this inrmal, and entails arical time-series ofof output to thesiness cycles. Thedecompositions ofnt in demand and components of unemployment are station-

    7.207.001950 1960 1970 1980

    FIGURE 7. OUTPUT FLUCTUATIONSABSENTDEMAND

    0.100.080.060.040.02 v0.007

    -0.04-0.06-0.08-0.101950 1960 1970 1980

    FIGURE 8. OUTPUT FLUCTUATIONSDUE TODEMAND

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    Structural VARV i d i i

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    Variance decomposition

    The k quarter-ahead forecast error in output is defined as thedifference between the actual value of output and its VAR-basedforecast.

    Variance decompositionConsider the VAR(1): yt = c + yt1 + t where the residuals aresome linear combinations of structural shocks ut (t = But).

    Compute k = yt+k Et (yt+k) with respect to ut+1, ut+2, . . . ut+k.

    How to compute the contribution of the ith

    structural shock on the jth

    endogenous variable?

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    Structural VARV t A t R i I l

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    Vector Auto-Regressions:Impulse responses

    66 THE AMERICAN ECONOMIC RE VIEW SEPTEMBER 1989TABLE 2-VARIANCE DECOMPOSITION OF OUTPUT ND UNEMPLOYMENT

    (CHANGE IN OUTPUT GROWTH AT 1973/1974; UNEMPLOYMENT DETRENDED)Percentage of Variance Due to Demand:Horizon(Quarters) Output Unemployment

    1 99.0 51.9(76.9,99.7) (35.8,77.6)2 99.6 63.9(78.4,99.9) (41.8,80.3)3 99.0 73.8(76.0,99.6) (46.2,85.6)4 97.9 80.2(71.0,98.9) (49.7,89.5)8 81.7 87.3(46.3,87.0) (53.6,92.9)12 67.6 86.2(30.9,73.9) (52.9,92.1)40 39.3 85.6(7.5,39.3) (52.6,91.6)

    TABLE 2A-VARIANCE DECOMPOSITION OF OUTPUT AND UNEMPLOYMENT(No DUMMY BREAK, TIME TREND IN UNEMPLOYMENT)Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 45 / 55

    Structural VARSmets and Tsatsaronis (1997)

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    Smets and Tsatsaronis (1997)

    Why does the yield curve predict economic activity? BIS WorkingPaper No.49.

    Objective: Investigating why the slope of the yield curve predictsfuture economic activity in Germany and the United States.

    Methodology: A structural VAR is used to identify aggregate supply,aggregate demand, monetary policy and inflation scare shocks and toanalyse their effects on the real, nominal and term premiumcomponents of the term spread and on output.

    Findings: In both countries demand and monetary-policy shockscontribute to the covariance between output growth and the laggedterm spread, while inflation scares do not.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 46 / 55

    Structural VARYield curve slope (10yr 3mth) vs Output gap Euro area data Source: OECD

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    Yield-curve slope (10yr-3mth) vs. Output gap, Euro area data, Source: OECD

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    Underlying theoretical model

    The authors argue that their model and in particular the restrictionsthey use is consistent with a semi-structural model that reads:

    yt = yt + st (Aggregate supply)

    yt = 1yt1 + 2yt2 + (1 1 2)yt3 4t1 + st(IS)

    it t = 1 (it1 t1) + 2t + 3 (yt yt) + it(Taylor rule)

    Rt = t +1

    N

    Ni=1

    Ett+i + t(Fisher equation)

    t = 1t + (1 1)Ett+

    1 + 2(yt1 yt1)(Phillips curve)

    Rt = Et

    Ni=1

    it+i

    (expectation hypothesis)

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 48 / 55

    Structural VARVector Auto-Regressions:Impulse responses

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    Vector Auto-Regressions:Impulse responses

    The identification suggested by the model calls for a mixture of shortand long-run zero restrictions.

    The assumption of a vertical long-run Phillips curve implies thatdemand shocks and nominal shocks (which include monetary-policyand inflation-scare shocks) have no long-run impact on the level of

    real output.Supply innovations are thus the source of all permanent shocks tooutput.

    Demand shocks are distinguished from nominal shocks by the

    assumption that the latter do not contemporaneously aff

    ect realoutput.

    Finally, the authors assume that monetary authorities do not respondcontemporaneously (i.e. within the quarter) to inflation scares.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 49 / 55

    Structural VARThe effect of a supply shock

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    The effect of a supply shock

    1.6

    0.8

    0

    0.8

    1.6

    1.0

    0.5

    0

    0.5

    1.0

    0.8

    0.4

    0

    0.4

    0.8

    0.8

    0.4

    0

    0.4

    0.8

    Germany GermanyUnited States United States

    Output

    Inflation

    Term spread

    Real component

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    Structural VARThe effect of a supply shock

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    The effect of a supply shock

    1.0

    0.5

    0

    0.5

    1.0

    1.0

    0.5

    0

    0.5

    1.0

    0.8

    0.4

    0

    0.4

    0.8

    0.8

    0.4

    0

    0.4

    0.8

    Short rate

    Long rate

    Inflation component

    Term premium

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    Structural VARThe effect of a demand shock

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    1.6

    0.8

    0

    0.8

    1.6

    1.0

    0.5

    0

    0.5

    1.0

    0.8

    0.4

    0

    0.4

    0.8

    0.8

    0.4

    0

    0.4

    0.8

    Germany GermanyUnited States United States

    Output

    Inflation

    Term spread

    Real component

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 52 / 55

    Structural VARThe effect of a demand shock

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    1.0

    0.5

    0

    0.5

    1.0

    1.0

    0.5

    0

    0.5

    1.0

    0.8

    0.4

    0

    0.4

    0.8

    0.8

    0.4

    0

    0.4

    0.8

    Short rate

    Long rate

    Inflation component

    Term premium

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 53 / 55

    Structural VARDecomposition of term-spread/output-growth covariance

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    p p / p g

    0.1

    0

    0.1

    0.2

    0.3

    0.4

    0.5

    0.6

    0 1 2 3 4 5 6 7 8 9 0.1

    0

    0.1

    0.2

    0.3

    0.4

    0.5

    0.6

    0 1 2 3 4 5 6 7 8 9

    Covarianceof which:

    SupplyDemand

    PolicyInflation scare

    Lags (in quarters)

    Note: The unconditional covariance between the current output growth and lagged term spread (solid line) is decomposed tothe contributions of the four structural shocks identified in the VAR.

    Germany United States

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 54 / 55

    References

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    Bhar, R. and Hamori, S. (2005). Empirical Techniques in Finance. Ed. SpringerFinance.

    Blanchard, O. and Quah, D. (1989). The Dynamic Effects of Aggregate Demandand Supply Disturbances. American Economic Review, vol. 79.

    Dedola, L. and Lippi, F. (2005). The monetary transmission mechanism: Evidencefrom the industries of five OECD countries. European Economic Review, vol. 49(6).

    Gal, J. (1992). How well does the IS-LM model fit postwar US data? QuarterlyJournal of Economics.

    Gerlach, S. and F. Smets (1995). The monetary transmission mechanism: evidencefrom the G7 countries. CEPR Discussion Paper, no. 1219.

    Granger, C. (1969). Prediction with a Generalized Cost of Error Function.Operational Research Quarterly, vol. 20.

    Hamilton, J. (1994). Time Series Analysis. Princeton University Press.

    Sims, C. (1980). Macroeconomics and Reality. Econometrica, vol. 48.

    Smets, F. and Tsatsaronis, K. (1997). Why does the yield curve predict economicactivity? BIS Working Paper No. 49.

    Jean-Paul Renne (Banque de France) Structural VAR and Applications ENSTA, 22 January 2010 55 / 55