Andre Achim

Personal Information

Full Name

André Achim

Affiliation

Université du Québec à Montréal

Location

Montréal, Canada

Why are you interested in structural equation modeling?

I am a retired, but still active intellectually, professor in Psychology. When I was teaching advanced statistics, I used Mx to introduce SEM to students. I continue working on statistical development. I the short term, I want to investigate implementing PARAFAC (Parallel Factor Analysis) in SEM, to further my own understanding and to find out tricks to reduce the number of trivially equivalent but mathematically distinct minima in the OpenMx implementation. When working with convariance matrices, setting a factor loading to 1 may solve the polarity indeterminacy of a factor that is allowed to load on all observed variables, but factor permutation remains a source of multiple optima. Since PARAFAC rests on assumptions of non-proportional factor variances across groups, it seems that a SEM implementation with LR confidence intervals could indicate, by turning out huge, when the assumption does not hold. It is not clear how the LR based confidence intervals can be fooled by the numerous optima.

Why are you interested in OpenMx?

I was very pleased by MX when it ran under Windows. When I discovered the existence of Onyx, I recommended it to the person who inherited from my grad statistical course.

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History

Member for

3 years 2 months