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# Re: st: RE: nonlinear regression using GMM

 From "JVerkuilen (Gmail)" To statalist@hsphsun2.harvard.edu Subject Re: st: RE: nonlinear regression using GMM Date Wed, 2 Jan 2013 09:43:16 -0500

```On Wed, Jan 2, 2013 at 9:30 AM, Feiveson, Alan H. (JSC-SK311)
<alan.h.feiveson@nasa.gov> wrote:
> Usman -I assume what you have written is the right-hand side of E(Y|DP, lr1, etc.) where Y is your dependent variable. If so, this looks linear to me if you re-parameterize as follows:
>
>
> E(Y'|lr1, DP, etc.) = A0*w1*DP + A1*DP*lr1 + A2*DP*w2 + A3*DP*w3 + A4*DP*y1 + A5*DP*y2 + A6*DP*y3
>
> where Y' = Y - lr1 and where A0 = {a0}*{a1}, A1 = {a0}, A2 = {a0}*{a2},  etc.
>
>
> Thus, you have a an equation that is linear in 7 parameters (A0, A1, .., A6)

I suppose it would depend on the error process that is assumed. So if
you have a fully multiplicative model the notion is that the errors
are multiplicative too. If that's not what's assumed the expected
value structure may be linearizable, but the error term may not. So

E(y|x) = exp(x' b) + u

is not linearizable while

E(y|x) = exp(x' b + u)

is. Thus I think the original poster needs to decide what the model
is, not just the mean structure.
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