Quantitative lunch -- Dr. Steve Boker.

OpenMx now allows the estimation of structural equation models that include products of variables; both manifest and latent. While the definition variable method has been used to include products of manifest variables for more than 20 years, the inclusion of products of latent variables has been a recent development. There are some identification issues to pay attention to, but with sensible constraints, these can be overcome. A large simulation shows that parameter point estimates for products of variables are unbiased. Also, normal theory standard errors have expected coverage unless the model is using the products of variables to estimate multilevel structure. Multilevel standard errors for products of variables are, as yet, an open problem.