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I have a question about the difference between structural equation modeling and mixed effects models.

What I'm trying to do is to use anatomical data (e.g. volume of a certain brain region) to explain performance in a cognitive test while controlling for age, sex, education level etc. I want to know how strongly the brain region volume influences performance and ideally to make an inference about causality by controlling for other factors. SEM and mixed effect models seemed like appropriate methods to me but I don't see how they would give me different information.

I'd appreciate if someone could explain this, or recommend any reading about the comparison of these methods, or maybe you want to suggest a different method altogether (e.g. to find out how much of the variance of cognitive performance is explained by that brain region volume). Thanks!

EDIT: To be more precise in case it matters: there are 5 different cognitive tests and 5 different anatomical measures, both sets have been measured twice (different years). I don't know if there is a good way to incorporate everything into one analysis or if I need to do 5x5 analyses.

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  • $\begingroup$ As described, your analysis doesn't need SEM or mixed effects modelling. Multiple linear regression, with test performance as the outcome and brain volume, age, sex, and education level as predictors, will answer your question. $\endgroup$
    – Eoin
    Aug 18 '21 at 9:02
  • $\begingroup$ How many times do subjects perform the test(s) ? Are the tests the same each time ? Are they the tests the same for each subject? $\endgroup$
    – Wayne B
    Aug 18 '21 at 9:12
  • $\begingroup$ @WayneB 2 times and it's an option to look at the changes but I didn't mention that to avoid making it more complicated - but an ideal full analysis of everything we have would include analyzing how the change in volume between these two years impacts/explains the change in performance. The tests are all the same for each subject and also for each of the two time points (there are a handful of different tests that everyone does at each timpoint, I thought about doing the same analysis once for each) $\endgroup$
    – AS91
    Aug 18 '21 at 12:49
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Structural equation models and mixed effects models can be equivalent. My favorite reference on this is: Have Multilevel Models Been Structural Equation Models All Along? by Curran.

What analysis is best depends on what hypothesis you want to test. It's not possible to say without more details.

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