Hello, I'm still a little stuck with specifying the model I want. Participants were tested under 2 Delivery conditions (B and M) at a variety of Speeds. I'm interested in how dv varies with speed and delivery type and in individual differences. I expect greater change in dv with speed for the B condition and greater subject to subject variability in the B condition than the M condition. I have tried some simple models but don't understand how to specify what I want: A model that has correlated random effects AND different residual variance for each level of delivery (or is that implicit in model 1)? model 1: correlated random effects fm1 = lmer(dv ~ Speed*Delivery + (Speed | Participant)) model 2: uncorrelated random effects fm2 = lmer(dv ~ Speed*Delivery + (1 | Participant) + (0 + Speed | Participant)) model 3: same as model 2 but with different residual variance for each level of delivery (where Bind and Mind are indices of B and M - similar to https://stat.ethz.ch/pipermail/r-sig-mixed-models/2007q3/000248.html) fm3 = lmer(dv ~ Speed*Delivery + (0 + Bind | Participant) + (0 + Mind | Participant) + (0 + Speed | Participant)) Thank you so much, James
Is it possible to specify a model with correlated random effects and different residual variance for 2 conditions?
1 message · James Croft