No, I haven't seen this done elsewhere. It is providing the flexibility that the usual repeated measurement software have with individually-varying times of observations in a long format, 2-level approach to growth modeling - but doing this in a single-level model in the more flexible wide format. So getting a random slope for a random time variable. I guess that is pretty unique and maybe we should have written about it to tout it.
Jon Heron posted on Tuesday, March 01, 2016 - 11:56 pm
I am contemplating adding this to a growth modelling lecture I am writing so wanted to make doubly-certain I understood what was happening.
Is that the nub of the issue, it's treating age as a time-varying covariate with a wave-invariant random effect on the repeated measure.