[Rd] Residual DF of NLS models (PR#14194)

[Prof Brian Ripley]

Can we please have a reproducible example (as we did ask in the 
FAQ, the posting guide ...).

On Tue, 26 Jan 2010, han at enfor.dk wrote:

> Full_Name: Henrik Aalborg Nielsen
> Version: 2.10
> OS: Linux (SLES 10 / openSUSE 11.1)
> Submission from: (NULL) (77.66.63.89)
>
>
> There seems to be a bug in df.residual.nls which is triggered when nls is called
> with argument na.action = na.exclude; in that case 'resid(object)' will contain
> NA-values which should be disregarded when counting the number of residuals:
>
> df.residual.nls <- function(object, ...) {
>    w <- object$weights
>    n <- if(!is.null(w)) sum(w != 0) else length(resid(object))
>    n - length(coef(object))
> }
>
> The bug cause the F-test of anova.nls to be wrong.
>
> Replace 'length(resid(object))' with 'sum(!is.na(resid(object)))' ?
>
> ... and thank you for producing this fantastic software!
>
> BR
> Henrik
>
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>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
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