Hi All,
I'm trying to understand the relationship between multivariate ACE models (e.g., Cholesky model fit to two phenotypes) and multilevel behavior genetic models. Is there a formal comparison somewhere?
My sense is that multivariate ACE models conflate within and between pair variance. A and C could capture within and between effects while E captures the within pair effects. E will map right onto the within pair effect in the multilevel model (MLM). Is all this correct?
I think A and C are estimated at the within pair level in the MLM, though I saw one paper in which it looked like they were estimated at both levels. Is this correct? And, how does C estimated from a multivariate ACE model relate to the twin pair level deviance from the population mean in the MLM? I don't think they are equal but am not sure.
Any help is greatly appreciated!
-George