I’m quite new to R and I have a following problem:
I have a simple 2-factor linear model:
# factor1 has 8 categorical values, factor2 has 6 categories Rate ~ factor1 + factor2 model1 <- lm(Rate~factor1+factor2, data=myData)
And want to put constraints SUM of factor1 coefficients = 0, the same for factor2.
None of the manuals gives any clue how to do this.
I found a link to similar problem here but it is different and I couldnt figure out how to modify it…
You can do this using contrasts:
?contr.sum for more information.
UPDATE: A little googling reveals a page which might be a little clearer:
- Samuel E. Buttrey, Setting and Keeping Contrasts