Please also provide the following information in addition to your question:
- Operating System: MacOS High Sierra
- brms Version: 2.5.0
Am trying to execute dyadic growth curve analysis in brms. Specifically, hoping to fit a model like the following that is done in nlme.
dyadGC <- lme(Y ~ GENDER + TIME + GENDER*TIME, data = data, random = ~ GenderS + GenderS:TIME - 1|dyadid, correlation = corCompSymm(form = ~1|dyadid/obsid), weights = varIdent(form = ~1|GenderS), na.action = na.omit)
Where GENDER is contrast coded (-1 and 1) and GenderS is a variable containing strings that indicate “Male” and “Female”. I know that correlation/residual structures are a feature request that is still open, but is there already there a way to fit something similar without the heterogenous compound symmetry correlation structure (e.g., replacing it with the AR(1) structure possibly)?
I have tried the following:
formula <- bf(y ~ TIME + GENDER + GENDER*TIME + (0 + genderS + genderS*TIME | hhid)) m1 <- brm(formula=formula, data=data, chains = 1, autocor = cor_ar(~ TIME | genderS), cov=TRUE)
But this seems to be a slightly different specification. I was hoping someone could offer some advice.