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Dear Mike & colleagues,
I conducted moderator analyses with OSMASEM with several moderators. When I performed OSMASEM with these moderators simultaneously and separately, it showed different estimates for moderators. Which one should be preferred?
I attached R-code and data.
Thanks for your time and patience.
Dear Dabiriyan,
This is similar to the case in multiple regression. The results are likely to be different when testing all predictors or one predictor at a time. In your case, only Individualism is statistically significant. You may focus on it.
Best,
Mike
Dear Mike,
Thank you very much for your reply. I really appreciate it.
Dear Mike,
I have a fake dataset I made myself to try out the OSMASEM models. There are missing correlations and missing values in the moderator. My questions are:
can OSMASEM handle missing values in moderator? the code with missing moderator values seems working, but how does the missing moderator values handled?
I followed your OSMASEM moderation code in ' MASEM on Nohe et al. (2015) data Suzanne Jak and Mike Cheung June 17, 2020 '. For the moderation effect, you seem to have 4 lines of results corresponding to the 4 paths in the Ax, so I expect I will have 3 lines of results since I have 3 paths in the Ax. However, I got only one line of result with the name 'moderated':
> summary(osmasem2)
Summary of moderating all
free parameters:
name matrix row col Estimate Std.Error A z value Pr(>|z|)
1 medONx A0 med x -0.2116346 14.247970 -0.014853667 0.9881489
2 yONx A0 y x 0.8599042 5.358775 0.160466578 0.8725135
3 yONmed A0 y med 0.2461819 26.169723 0.009407127 0.9924943
4 xWITHx S0 x x 0.2009616 25.820149 0.007783129 0.9937900
5 moderated Ax1 2 1 0.1000000 NA ! NA NA
6 Tau1_1 vecTau1 1 1 -2.3411371 6.558308 -0.356972730 0.7211122
7 Tau1_2 vecTau1 2 1 -0.8892047 15.058792 -0.059048869 0.9529132
8 Tau1_3 vecTau1 3 1 -1.0218680 13.109379 -0.077949382 0.9378683
The name of the term and the number of the terms are both not correct.
I guess the fake data caused the NAs, but I am not sure about the ' moderated ' term. I am using OpenMx version number: 2.18.1, whereas you used OpenMx version number: 2.17.4 , does that matter?
Thank you very much.
Hi Ya,
1) OSMASEM treats the moderators as definition variables. Therefore, NA is not allowed in the moderators.
2) I have made some changes in your script. Please see the attached one.
Best,
Mike