Re: [R] Fit values for NA's in linear regression

From: Liaw, Andy <andy_liaw_at_merck.com>
Date: Sat 18 Jun 2005 - 02:38:53 EST


It depends on the na.action used in lm(), which defaults to na.omit. Here's an example:

> x <- c(1:5, NA, 7:10)
> y <- rnorm(x)
> fitted(lm(y ~ x))

          1 2 3 4 5 7 8
 0.68680104 0.47913875 0.27147646 0.06381417 -0.14384812 -0.55917271 -0.76683500

          9 10
-0.97449729 -1.18215958
> fitted(lm(y ~ x, na.action=na.exclude))

          1 2 3 4 5 6 7
 0.68680104 0.47913875 0.27147646 0.06381417 -0.14384812 NA -0.55917271

          8 9 10
-0.76683500 -0.97449729 -1.18215958

Andy

> From: Luca Wacker
>
> Hi,
>
> To obtain estimates for some missing values in my data I fitted a
> linear regression and then used the command fitted(model) to get the
> fitted values from the model, but R doesn't return any values for the
> NA's. I can calculate the fitted values from the estimates obtained
> from the summary of model, but that's not very handy. Is
> there a way to
> include the missing values in the analysis and get fitted values for
> the NA's? I tried to use with the function na.action, but that didn't
> work.
>
>
> thanks
>
> Luca
>
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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 Sat Jun 18 04:13:02 2005

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