If you fit a linear model or a mixed model there are different types of codings available to transform a categorical or nominal varibale into a number of variables for which paramaters are estimated, such as dummy conding (the R default) and effects coding.
I heard that effects coding (sometimes called deviation or contrast coding) is preferred when you have interactions, but what are the possible contrasts and when would you use which type of contrast?
The context is mixed modeling in R using
lme4, but I think broader responses are fine. Sorry, if I missed a similar question.