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simple question

PostPosted: Sat Aug 08, 2009 10:39 am
by hkg166
I must have a stupid mistake somewhere. This is the simple model without labor supply.
The policy function should give me y(t)= .36 * k(t-1) +Z(t)
where .36 is the labor share.
Instead it is giving me y(t) = .0526 k(t-1) + Z(t)
and interestingly, .0526 is the interest rate.

Suggestions would be greatly appreciated.

var Y K e_A C R ;
varexo eps_A ;
parameters beta delta alpha rho_A nu ;
beta=0.95;
delta=0.0;
alpha=0.36;
nu=2.0;
rho_A=0.85;


model;
Y=exp(e_A)*K(-1)^alpha;
Y=C+ K-(1-delta)*K(-1);
1=(C(+1)/C)^(-nu)*beta*(1+R(+1));
R=alpha*K(-1)^(alpha-1)-delta;
e_A=rho_A* e_A(-1)+eps_A;
end;


initval;
K=10;
C=2.09;
e_A=0;
end;


steady;


shocks;
var eps_A; stderr sqrt(.04);
end;


stoch_simul(order=1,nograph,nocorr,nomoments);


POLICY AND TRANSITION FUNCTIONS
Y K e_A C R
Constant 2.949299 20.173181 0 2.949299 0.052632
K (-1) 0.052632 0.971856 0 0.080776 -0.001670
e_A(-1) 2.506904 1.613092 0.850000 0.893812 0
eps_A 2.949299 1.897755 1.000000 1.051544 0

Re: simple question

PostPosted: Tue Aug 25, 2009 1:11 pm
by SébastienVillemot
How do you know that the policy function should be:
Y(t) = 0.36*K(-1) + ... ?

Best,

Re: simple question

PostPosted: Tue Aug 25, 2009 1:23 pm
by hkg166
It is .36 because it is the share of capital. I figured this out. It is linear vs log linear. Thanks.

model;
Y=e_A+alpha*K(-1);
Y=log(exp(C)+ exp(K)-(1-delta)*exp(K(-1)));
0=-nu*(C(+1)-C)+log(beta)+log(1+R(+1)-delta);
R=alpha*exp(Y)/exp(K(-1));
e_A=rho_A* e_A(-1)+eps_A;
end;


POLICY AND TRANSITION FUNCTIONS
Y K e_A C R
Constant 0.862978 2.397160 0 0.739749 0.077627
K (-1) 0.360000 0.955662 0 0.508652 -0.049682
e_A(-1) 0.850000 0.129528 0.850000 0.282004 0.065983
eps_A 1.000000 0.152386 1.000000 0.331769 0.077627