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No user picture. iana Joined: 10/16/2021

How to generate A matrice and S matrice for the second stage of TSSEM?

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metaSEM

Hi Milke and all,

I'm trying to run a TSSEM to examine the mediation effect for a meta-analysis. However, I'm not sure what's the appropriate way to create the A matrice and S matrice needed for stage 2. Would you please advise?

Posted on
No user picture. Eva CUI Joined: 03/22/2022

Acceptatble Mediation Model?

Forums
metaSEM

Hello all,

I am doing multiple mediatiors analysis. I am wondering if we can set the diag.contraints = FALSE?

1) Anyone notices that "diag.contraints = TRUE" may lead to unfitted model?

2) What is the criteria of the acceptable MASEM model? Would it be stricter compared with SEM? Below are my resutls. Is it acceptatble (Chi-X2 ratio is very high)?

Chi-X2 (df = 5) = 115.55, p <.001, CFI = 0.94, NNFI = 0.81, RMSEA = 0.06, SRMR = 0.08.

Thank you so much for your attention and help!

Best regards,
Eva

Posted on
No user picture. anyuliu Joined: 12/11/2018

Error when summarize tssem1 results

Forums
metaSEM

I have a 26*26 matrix for 10 studies with many missing values. It costed a few hours to run the random effect model of tssem1. When I summarized the results by "summary(random1)" , the error "Error in chol.default(V) : 'a' must have dims > 0" appereared. I also noiced that many correlications are presented as "0.1".

Could anyone help to fix the error? May I know that those "0.1"s in the correlaiton matrix are resulted from the many "NA"s in the input matrices? Thank you for your great help.

The data and code are attached.

Posted on
No user picture. Eva CUI Joined: 03/22/2022

metaSEM_Indirect effects via multiple mediators

Forums
metaSEM

Hello all,

I am intereseted to test the indirect effects with multiple sequential mediators. I am wondering how would it possible to estiamte it? I tried to use the R code below, but there are warnings listed below. It would be highly appreciated if anyone would provide your thoughts? Thank you so much in advance!

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No user picture. jf.martin Joined: 03/18/2022

Regression analysis

Forums
metaSEM

Dear Community,

I’m trying to fit a regression model by regressing the true effect size y_strength on the true effect size y_MEP (see attached dataset). I use the following code to remove NA and unnecessary columns, as well as to specify the SEM in OpenMx:

library(metaSEM)

library(readr)

Posted on
No user picture. tylermc5 Joined: 03/08/2022

'Fit is not finite' Error Message

Forums
metaSEM

Hi there,
I am running a multivariate meta analysis and running into an error code I cannot seem to resolve. In prior error messages related to this content, others have noted negative or zero values in the covariance matrix, but I'm not seeing any from the output. Any/all help you could provide would be amazing!

Context: Looking at two types of memory tasks (forward and backward) comparing deaf and hearing participants using Hedge's g effect size.

Posted on
No user picture. Eva CUI Joined: 03/22/2022

Inequality of the sample size

Forums
metaSEM

Hello,

I am conducting a MASEM study using TSSEM (random-effects) approach. There are in total six variables involved (i.e., PS, PA, MA, Voc, WR, and RC) in the hypothesized model. In the tested model, PS is the predictor and RA serves as the latent variable, which can be loaded on WR and RC. And the PA, MA, Voc would serve as the mediators. I do have several questions listed below:

Posted on
No user picture. EmilieRH Joined: 09/24/2020

umxGxE with quadratic mean effects

Forums
umx

Hi all,

Is it possible to modify the umxGxE function to include quadratic mean effects in the case where the twins do not share the moderator? If not, can anyone refer me to an R script that estimates Purcell’s original ACE-XYZ-M model with quadratic mean effects?

Best regards,
Emilie

Posted on
No user picture. j.aitken Joined: 06/30/2021

Testing for Partial Invariance

Forums
metaSEM

Hello,

My research team is interested in testing a mediation model and comparing the coefficients of A paths (from IV to Mediators) as well as the coefficients of B paths (from Mediators to DV). To do so, we estimated a model without B paths and constrained all A paths to be equal and then compared the fit of that model to one where A paths were not constrained. Similarly, we tested a model (including A paths) where B paths were constrained versus one where they were not.

Posted on
No user picture. g.iuli Joined: 11/13/2021

Testing homogeneity with homoStat!

Forums
metaSEM

Hi everyone,
I conducted a two-stage metaSEM with fixed effect model, since the random effect model reported estimation problem (after more then 5 hours running the first stage it never gave an output!).

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