[R] subset

[Ngayee J Law]

Dear list,

I have a simple question. If I need to run linear regression on a subset of
the dataset, will
the following two commands give the same output:

lm(y ~ as.factor(x1) + as.factor(x2), data, subset = z==Z[1])

and

lm(y ~ as.factor(x1) + as.factor(x2), data[data$z==Z[1],] )


I have got different results running the two commands. Am I missing
something here, or it
there a bug on the option subset?

Thanks for the help!

- Jackie




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