[R] Adding predicted values as a new variable in a data frame

[Gabor Grothendieck]

Specify na.action = na.exlude, e.g.

> x <- y <- 1:10; x[5] <- NA
> fitted(lm(y ~ x, na.action = na.exclude))
 1  2  3  4  5  6  7  8  9 10
 1  2  3  4 NA  6  7  8  9 10

On 9/14/06, Robi Ragan <robi.ragan at gmail.com> wrote:
> I am running a regression:
>
> ols.reg1 <- lm(y ~ x1 + x2 + x3 + x4)
>
> on a data.frame
>
> and then generating fitted values:
>
> y.hat <- ols.reg1$fitted.values
>
> Then I would like to add these fitted values to the data.frame as a
> new variable. The problem is that when the values are predicted the
> resulting output has too few rows. for some reason certian
> observations do not get predicted values. So this shrinks the column
> down and I then cannot combine the output into the original
> data.frame.
>
> If someone could please help I would apreciate it. Stata automatically
> adds a new column to the data set when you find the fitted values. So
> having to fight with R just to do something I used to routimely do has
> made me think of turning back to the dark side. I hope I have just
> missed something trival in all the help files I have been
> looking through.
>
> Thanks,
>
>
> --
>
> Robi Ragan
> Graduate Student
> Department of Economics
> Department of Political Science
> The University of Georgia
>
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