What is the goal of the analysis? If you want to draw formal inference
(e.g., reporting p-values), it's dangerous to `eyeball' a model from the
data, as that will most likely bias the p-values.
If all you want is a quadratic polynomial, that's not a nonlinear model, and
should be fitted with lm (or lme if you have random effects) with a poly()
term.
Andy
> From: Savitri Appana
>
> Hi everyone,
>
> I need some help fitting a quadratic polynomial model
> with NLME.
>
> I've seen that NLME has some of the common nonlinear
> models built-in, but I don't think I can use one of
> these models. These built-in models are modeling
> curves with an apparent "asymptote" or more "S-shaped"
> or something more complicated than what I need. The
> data I'm modeling has more of a quadratic look.
>
> I'd greatly appreciate any comments or suggestions.
> Thank you very much in advance.
>
>
>
> Savi A.
>
> Statistician
>
> Jefferson Labs, FDA
>
> Ph: 870-543-7623
>
> E-mail: saviappana@yahoo.com
>
>
>
>
>
>
>
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