[R] Eliminate cases in a subset of a dataframe

Hollix Holger.steinmetz at web.de
Mon Sep 14 16:57:40 CEST 2009

Hi folks,

I created a subset of a dataframe (i.e., selected only men):

subdata <- subset(data,data$gender==1)

After a residual diagnostic of a regression analysis, I detected three

linmod <- lm(y ~ x, data=subdata)

Say, the cases 11,22, and 33 were outliers.

Here comes the problem: When I want to exclude these three cases in a
further regression analysis, 
- for instance with linmod2 <- lm(y[-c(11,22,33)] ~ x[-c(11,22,33)],
data=subdata) - it does not work.

I guess this has something to do with this strange "row.names"-vector which
has been added to the dataframe when creating the subset. I find it very
strange why R gives the case numbers in the diagnostics but then doesn't
allow me to use these numbers for further exclusion. 

Can anybody tell me:
1. what this row.names vector is
2. How I can refer to cases after creating a subset (e.g., in order to
exclude them).

Many thanks in advance,
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