Hi, all.
I derived an equation such as y_t = E_t (x_t+1)*(z_t+1) ]
that I coded this equation as y = x(+1)*z(+1) .
However, I think this coding would mean this ; y_t = E_t[x_t+1]*E_t[z_t+1]
So, to avoid such confusion, I coded the equation as y = x(+1)*z(+1) +c
where ‘c’ is a constant variable represanting the covariance of x and z.
I’m not sure whether it is a reasonable way or not.
Thanks for reading and hope for any reply.
Hi,
You are wrong. Let s_t be a vector of endogenous variables. Dynare
consider problems of the following form:
E_t [f(s_{t-1},s_t,s_{t+1},e_t,e_{t+1})] = 0
where f is a function defining the model and e is the structural
innovation. So Dynare interprets:
y = x(+1)*z(+1)
as
y_t = E_t (x_t+1)*(z_t+1) ]
But if in your model you have something like:
y_t = E_t[x_t+1]*E_t[z_t+1]
you have to declare two auxiliary variables:
Ex = x(1)
Ez = z(1)
and write:
y = Ex*Ez
Best,
Stéphane.