On 24/09/09 22:34 PM, "Hamish" <hwil...@ucsd.edu> wrote:
>
> I want to force a =1 and b= -1, yielding:
>
>
> N ~ 1*Mass + (-1)*Temp + c*Precipitation + {d,e,f,g}*DIET
>
I think you want to have
N ~ offset(Mass) + offset(-Temp) + Precipitation + DIET
Most *lm functions know offset. However, you must be very careful especially
with links other than identity. Moreover, you must be sure that this really
is what you're looking for: the above expression would be equivalent to
offset(Mass-Temp) and is Mass-Temp really something you think you want to
fix.
>
> and then see what the values of the other parameters (c-g) turn out to be,
> as well as the model fit when using the forced parameters in conjunction
> with the free parameters.
>
Cheers, Jari Oksanen
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