[R] Constrain coefs. in linear model to sum to 0
Gorjanc Gregor
Gregor.Gorjanc at bfro.uni-lj.si
Mon Aug 7 10:37:16 CEST 2006
Hello!
I would like to use constrain to sum coeficients of a factor to 0 instead
of classical corner contraint i.e. I would like to fit a model like
lm(y ~ 1 + effectA + effectB)
and say get parameters
intercept
effectA_1
effectA_2
effectB_1
effectB_2
effectB_3
where effectA_1 represents deviation of level A_1 from intercept and
sum(effectA_1, effectA_2) = 0 and the same for factor B.
Is this possible to do?
Lep pozdrav / With regards,
Gregor Gorjanc
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University of Ljubljana PhD student
Biotechnical Faculty URI: http://www.bfro.uni-lj.si/MR/ggorjan
Zootechnical Department mail: gregor.gorjanc <at> bfro.uni-lj.si
Groblje 3 tel: +386 (0)1 72 17 861
SI-1230 Domzale fax: +386 (0)1 72 17 888
Slovenia, Europe
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"One must learn by doing the thing; for though you think you know it,
you have no certainty until you try." Sophocles ~ 450 B.C.
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