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Longitudinal and multi group studies

Posted: Mon Aug 26, 2019 12:09 pm
by shamilaj
Hi,

Please refer me to longitudinal studies that also used multi groups. I am trying to do a study using 2 groups and collected data during 2 different time points. I am looking for example studies to make sure what I am doing is correct.

Any help will be much appreciated.

Thank you.

Re: Longitudinal and multi group studies

Posted: Tue Aug 27, 2019 6:31 pm
by jmbecker
I'm not aware of longitudinal studies that use PLS-MGA. The problem is that PLS-MGA assumes independence of the groups. However, in a longitudinal setting groups are not independent, just like in a paired t-test.

If you have strictly paired data, I would rather model both time points in the same model (maybe even including autoregressive effects).

Re: Longitudinal and multi group studies

Posted: Wed Aug 28, 2019 7:56 pm
by shamilaj
Thank you very much Dr. Becker.

What you said makes sense. I did as you said and put both time points within the same model. To test difference between the 2 groups do I just look at p-value (condition 1 Vs condition 2) in the PLS-MGA or parametric test?

-Shamila

Re: Longitudinal and multi group studies

Posted: Sun Sep 01, 2019 9:05 am
by jmbecker
If you have everything in one model you can test parameters in t1 vs. t2 with the following approach
Rodríguez-Entrena, M., Schuberth, F., & Gelhard, C. (2018). Assessing statistical differences between parameters estimates in Partial Least Squares path modeling. Quality & quantity, 52(1), 57-69.

Re: Longitudinal and multi group studies

Posted: Sat Sep 07, 2019 8:22 pm
by shamilaj
Thank you very much Dr. Becker.

In this paper they talk about using MS Excel "in order to manually calculate the parameter difference for
every bootstrap sample" (p.63). I used SmartPLS 3.0 hence I think this operation is completed by the software itself. Correct me if I am wrong.

-Shamila