[R] forcing a zero level in contr.sum
David Winsemius
dwinsemius at comcast.net
Wed Jul 7 21:43:39 CEST 2010
On Jul 7, 2010, at 3:13 PM, Bond, Stephen wrote:
> I need to use contr.sum and observe that some levels are not
> statistically different from the overall mean of zero.
> What is the proper way of forcing the zero estimate? It seems the
> column corresponding to that level should become a column of zeros.
> Is there a way to achieve that without me constructing the design
> matrix?
> Thank you.
lm( formula = z ~ x + y + 0, ...) _might_ do something close to
what you want.
David Winsemius, MD
West Hartford, CT
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