[R] Tabulating Baseline Characteristics on specific observations

[David Winsemius]

On Sep 19, 2011, at 8:49 PM, justin jarvis wrote:

> I have a data set with many missing observations.  When I run a
> regression, R of course discards the observations (the whole row) that
> have "NA".  I want to tabulate some baseline characteristics (column
> means) but only for the observations that R used for the regression.
> I tried to recreate this data frame by using na.omit on the original
> data frame, but this will not work as this will discard an observation
> with an "NA" in any column, and not just in the covariates.
>
> In summary, I only want to remove observations that have an "NA" in
> the covariate columns.  Something like Stata's e(sample), as far as I

na.omit(subset(dfrm, select= <covariate-vector> )  # or equivalent

> can tell.
>
> Justin Jarvis
> PhD student, University of California, Irvine
>
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David Winsemius, MD
West Hartford, CT