non-conformable arguments error from lmer when trying to extract information from the model matrix
问题 I have some longitudinal data from which I'd like to get the predicted means at specified times. The model includes 2 terms, their interaction and a spline term for the time variable. When I try to obtain the predicted means, I get "Error in mm %*% fixef(m4) : non-conformable arguments" I've used the sleep data set from lmer to illustrate my problem. First, I import the data and create a variable "age" for my interaction sleep <- as.data.frame(sleepstudy) #get the sleep data # create fake