Added a function returning the prior and posterior densities of a dsge-var model, given the deep parameters and the dsge_prior_weight parameter.
git-svn-id: https://www.dynare.org/svn/dynare/dynare_v4@1740 ac1d8469-bf42-47a9-8791-bf33cf982152time-shift
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@ -1,5 +1,4 @@
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function [fval,cost_flag,info,PHI,SIGMAu,iXX] = DsgeVarLikelihood(xparam1,gend)
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function [fval,cost_flag,info,PHI,SIGMAu,iXX,prior] = DsgeVarLikelihood(xparam1,gend)
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% function [fval,cost_flag,info,PHI,SIGMAu,iXX] = DsgeVarLikelihood(xparam1,gend)
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% Evaluates the posterior kernel of the bvar-dsge model.
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%
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@ -14,14 +13,13 @@ function [fval,cost_flag,info,PHI,SIGMAu,iXX] = DsgeVarLikelihood(xparam1,gend)
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% o PHI [double] Stacked BVAR-DSGE autoregressive matrices (at the mode associated to xparam1).
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% o SIGMAu [double] Covariance matrix of the BVAR-DSGE (at the mode associated to xparam1).
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% o iXX [double] inv(X'X).
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% o prior [double] a matlab structure describing the dsge-var prior.
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%
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% SPECIAL REQUIREMENTS
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% None.
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%
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% part of DYNARE, copyright Dynare Team (2006-2008)
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% Gnu Public License.
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global bayestopt_ estim_params_ M_ options_
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nvx = estim_params_.nvx;
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@ -211,4 +209,13 @@ if (nargout == 6)
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else
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iXX = tmp2;
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end
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end
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if (nargout==7)
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iGXX = inv(GXX);
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prior.SIGMAstar = GYY - GYX*iGXX*GYX';
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prior.PHIstar = iGXX*transpose(GYX);
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prior.ArtificialSampleSize = fix(dsge_prior_weight*T);
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prior.DF = prior.ArtificialSampleSize - NumberOfParameters - NumberOfObservedVariables;
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prior.iGXX = iGXX;
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end
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@ -0,0 +1,79 @@
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function bvar = dsgevar_posterior_density(deep)
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% This function characterizes the posterior distribution of a bvar with
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% a dsge prior (as in Del Negro and Schorfheide 2003) for a given value
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% of the deep parameters (structural parameters + the size of the
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% shocks + dsge_prior_weight).
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%
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% INPUTS
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% deep: [double] a vector with the deep parameters.
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%
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% OUTPUTS
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% bvar: a matlab structure with prior and posterior densities.
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%
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% ALGORITHM
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% ...
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% SPECIAL REQUIREMENTS
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% none
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%
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%
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% part of DYNARE, copyright Dynare Team (1996-2007)
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% Gnu Public License.
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global options_ M_
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gend = options_.nobs;
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dsge_prior_weight = M_.params(strmatch('dsge_prior_weight',M_.param_names));
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DSGE_PRIOR_WEIGHT = floor(gend*(1+dsge_prior_weight));
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bvar.NumberOfLags = options_.varlag;
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bvar.NumberOfVariables = size(options_.varobs,1);
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bvar.Constant = 'no';
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bvar.NumberOfEstimatedParameters = bvar.NumberOfLags*bvar.NumberOfVariables;
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if
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bvar.Constant = 'yes';
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bvar.NumberOfEstimatedParameters = bvar.NumberOfEstimatedParameters + ...
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bvar.NumberOfVariables;
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end
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[fval,cost_flag,info,PHI,SIGMAu,iXX,prior] = DsgeVarLikelihood(deep',gend);
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% Conditionnal posterior density of the lagged matrices (given Sigma) ->
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% Matric-variate normal distribution.
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bvar.LaggedMatricesConditionalOnSigma.posterior.density = 'matric-variate normal';
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bvar.LaggedMatricesConditionalOnSigma.posterior.arg1 = PHI;
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bvar.LaggedMatricesConditionalOnSigma.posterior.arg2 = 'Sigma';
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bvar.LaggedMatricesConditionalOnSigma.posterior.arg3 = iXX;
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% Marginal posterior density of the covariance matrix -> Inverted Wishart.
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bvar.Sigma.posterior.density = 'inverse wishart';
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bvar.Sigma.posterior.arg1 = SIGMAu*DSGE_PRIOR_WEIGHT;
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bvar.Sigma.posterior.arg2 = DSGE_PRIOR_WEIGHT-bvar.NumberOfEstimatedParameters;
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% Marginal posterior density of the lagged matrices -> Generalized
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% Student distribution (See appendix B.5 in Zellner (1971)).
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bvar.LaggedMatrices.posterior.density = 'matric-variate student';
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bvar.LaggedMatrices.posterior.arg1 = inv(iXX);%P
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bvar.LaggedMatrices.posterior.arg2 = SIGMAu*DSGE_PRIOR_WEIGHT;%Q
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bvar.LaggedMatrices.posterior.arg3 = PHI;%M (posterior mean)
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bvar.LaggedMatrices.posterior.arg4 = DSGE_PRIOR_WEIGHT;%(sample size)
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% Conditionnal posterior density of the lagged matrices (given Sigma) ->
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% Matric-variate normal distribution.
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bvar.LaggedMatricesConditionalOnSigma.prior.density = 'matric-variate normal';
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bvar.LaggedMatricesConditionalOnSigma.prior.arg1 = prior.PHIstar;
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bvar.LaggedMatricesConditionalOnSigma.prior.arg2 = 'Sigma';
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bvar.LaggedMatricesConditionalOnSigma.prior.arg3 = prior.iGXX;
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% Marginal posterior density of the covariance matrix -> Inverted Wishart.
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bvar.Sigma.prior.density = 'inverse wishart';
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bvar.Sigma.prior.arg1 = prior.SIGMAstar*prior.ArtificialSampleSize;
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bvar.Sigma.prior.arg2 = prior.DF;
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% Marginal posterior density of the lagged matrices -> Generalized
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% Student distribution (See appendix B.5 in Zellner (1971)).
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bvar.LaggedMatrices.prior.density = 'matric-variate student';
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bvar.LaggedMatrices.prior.arg1 = inv(iGXX);%P
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bvar.LaggedMatrices.prior.arg2 = prior.SIGMAstar*prior.ArtificialSampleSize;%Q
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bvar.LaggedMatrices.prior.arg3 = prior.PHIstar;%M (posterior mean)
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bvar.LaggedMatrices.prior.arg4 = prior.ArtificialSampleSize;%(sample size)
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