## Effect size Linear mixed models GAMJj

### Effect size Linear mixed models GAMJj

I´m trying to do a LMM using Jamovi, but I can't find an option to report effect size. There are something to report it?

- mcfanda@gmail.com
**Posts:**482**Joined:**Thu Mar 23, 2017 9:24 pm

### Re: Effect size Linear mixed models GAMJj

Standarized effect sizes in lmm are not so straightforward. You can report the R-squared.

### Re: Effect size Linear mixed models GAMJj

How about this approach? https://cran.r-project.org/web/packages ... tics.html

- mcfanda@gmail.com
**Posts:**482**Joined:**Thu Mar 23, 2017 9:24 pm

### Re: Effect size Linear mixed models GAMJj

The approach in the link does not explain how to interpret the index. In LMM, in fact, the variance is partitioned in different levels. So, when one computes the partial eta-squared, it is not clear the proportion of what variance in represented. Furthermore, if an effect is also random, it is not clear whether one should take into the account the variance explained by the random coefficients (conditional effect) or only the fixed effect (marginal)

### Re: Effect size Linear mixed models GAMJj

Yes, it seems that there is a bit of controversy and that some alternative concepts may better explain the effect size in these cases.

R-squared is not available in post-hoc comparisons right? Would there be any alternative in this case?

What is the reason why Cohen's d is not available in the LMM but is available in the GLM for the same Jamovi package?

R-squared is not available in post-hoc comparisons right? Would there be any alternative in this case?

What is the reason why Cohen's d is not available in the LMM but is available in the GLM for the same Jamovi package?

- mcfanda@gmail.com
**Posts:**482**Joined:**Thu Mar 23, 2017 9:24 pm

### Re: Effect size Linear mixed models GAMJj

>> What is the reason why Cohen's d is not available in the LMM but is available in the GLM for the same Jamovi package?

Laziness of the developer (which is me). Cohen's d in LMM is cumbersome to implement because it has different formulas for different designs, but is definitely doable. I hope to get it done soon

Laziness of the developer (which is me). Cohen's d in LMM is cumbersome to implement because it has different formulas for different designs, but is definitely doable. I hope to get it done soon

### Re: Effect size Linear mixed models GAMJj

I wonder, why would the denominator for Cohen's d suffer from the same complication/ambiguity that other LMM effect-size measures suffer from? Why would the denominator for Cohen's d need to somehow account for variances explained by random coefficients?

- mcfanda@gmail.com
**Posts:**482**Joined:**Thu Mar 23, 2017 9:24 pm

### Re: Effect size Linear mixed models GAMJj

Thanks! (Also, I meant to write: "why wouldN'T the denominator for Cohen's d suffer from the same complication/ambiguity")