Re: [R] NA handling with lm

From: Adaikalavan Ramasamy <ramasamy_at_cancer.org.uk>
Date: Fri 29 Jul 2005 - 20:01:30 EST

Also have a look at this thread from last week https://stat.ethz.ch/pipermail/r-help/2005-July/074550.html

Regards, Adai

On Thu, 2005-07-28 at 18:59 +0200, Petr Pikal wrote:
> Hallo
>
> On 28 Jul 2005 at 18:44, Andreas Cordes wrote:
>
> > Hi,
> > I have a problem that is hopefully easily solvable, but I dont find
> > the clue in the documentation. I am examining a linear model. One of
> > the variables has NA values. Even though na.action=na.omit, i get NA
> > as results for this variable. Can I use lm in such a case to get
> > estimates? Or do I have to do some form of imputation before doing so?
> > Here is the call and the results, hope you can help. Best regards,
> > Andreas
> > ----------------------------------------------------------------------
> > ----------------------- lm(formula = ESSIK ~ ALTER + as.factor(S2) +
> > as.factor(S15A) +
> > as.factor(S8) + as.factor(LAND) + as.factor(S18B) +
> > as.factor(BERUF) + as.factor(KIRCHE) + as.factor(H_EINKOM) +
> > as.factor(PARTNERS), na.action = na.omit)
> >
> > Residuals:
> > Min 1Q Median 3Q Max
> > -17.0675 -2.0151 0.4267 2.7644 9.7333
> >
> > Coefficients: (2 not defined because of singularities)
>
> Problem is not in NA handling but that some of your coeficients
> can be represented as linear combination of other coeficients. You
> have to omit them.
>
> HTH
> Petr
>
>
> > Estimate Std. Error t value Pr(>|t|)
> > (Intercept) 23.755915 1.844110 12.882 < 2e-16 ***
> > [...]
> > as.factor(BERUF)7 -1.236836 0.701323 -1.764 0.077942 .
> > as.factor(KIRCHE)1 -0.811751 0.237699 -3.415 0.000649 ***
> > as.factor(H_EINKOM)2 NA NA NA NA
> > as.factor(H_EINKOM)3 NA NA NA NA
> > as.factor(PARTNERS)1 2.057070 0.342546 6.005 2.23e-09 ***
> >
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>
> Petr Pikal
> petr.pikal@precheza.cz
>
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R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Jul 29 20:17:24 2005

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