What are you trying to do?
Suppose, for example, that you have a categorical variable
representing 3 different age groups, and you want to estimate a linear
model. As long as R recognizes the variable as categorical (of class
"factor" or "ordered factor", R handles this automatically
using
"contrasts". If this is your question, I suggest you read about
"factors", "Formulae for Statistical Models" and
"Contrasts" in "An
Introduction to R", which is the upper-left choice after
'help.start()'
in recent versions of R (or downloadable from www.r-project.org ->
Documentation -> Manuals).
If you would like more help from this group, I believe you will
increase your chances of getting quickly the information you seek in you
PLEASE do read the posting guide!
"www.R-project.org/posting-guide.html".
hope this helps.
spencer graves
Oana Mocila wrote:
> Dear all,
>
> I have a problem when I was working on Age-Period-Cohort study in R. I
tried
> to put constraint to
> two coefficients on age (so that to solve the identification problem due to
> linear dependency). But
> I don't know how to do this in R(put constraint). If you could give me
some
> suggestion, it will be very helpful!
>
> Oana
>
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--
Spencer Graves, PhD
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