Dear all, I have a mixed model of the form: y[it]=a+b*z[i]+ai+(c+c[i])*x[it] ("i" refers to group and "t" to observation in group). zi are group-specific variables available only for a number of groups and "ai", "ci" denote the random effects on the intercept and slope respectively. Is there some way to drop b*zi for the missing value cases or some other way to deal with them? thank you! Irene
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