R help - Oct 2011 - Simple question regarding to specifying model

I have hunted around but cannot find the command which allows me to specify
parameters of a model.

For example,

model.m1 <- nls(y ~ alpha * x1/(beta + x1), data = data, start = list(beta
20, alpha = 120), trace = TRUE)

This will estimate the parameters, which allows to investigate the
residuals.

What I would like to do is fix the parameters to the data that I have
estimated elsewhere, to analyse their residuals. For example,

model.m2 <- y ~ 80 * x1/30 +x1 ??????

Thanks


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On Oct 12, 2011, at 2:25 PM, BvZ wrote:
> I have hunted around but cannot find the command which allows me to  
> specify
> parameters of a model.
>
> For example,
>
> model.m1 <- nls(y ~ alpha * x1/(beta + x1), data = data, start =  
> list(beta > 20, alpha = 120), trace = TRUE)
>
> This will estimate the parameters, which allows to investigate the
> residuals.
>
> What I would like to do is fix the parameters to the data that I have
> estimated elsewhere, to analyse their residuals. For example,
>
> model.m2 <- y ~ 80 * x1/30 +x1 ??????
Wouldn't this just be

resids <- predict(model.m1) - with( data,  80 * x1/30 +x1)

-- 

David Winsemius, MD
West Hartford, CT

Tried this, it does not seem to work.  

It is really simple what I am trying to do.  I have a pre-specified best-fit
line, and wish to run some diagnostic tests for goodness of fit.

I will play around with the predict function, thanks a lot David!

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