metaSEM

Hi Mike (and the rest of the forum),

Thanks so much for maintaining your metaSEM package!

I have been trying to fit a variation of a network meta-analysis model using your package. In particular, I need to impose specific constraints on the estimated between-studies covariance matrix. However, my question is not about the constraints that I'm imposing, but rather about a not positive definite error that I haven't been able to figure out.

Dear all,

I read in previous forum that it was possible to apply tssem2 over a given pooled correlation matrix with the function wls(), as it is a wrapper of tssem2.

I have found some inconsistent results when using wls() fuction, so I tried to take the pooled correlation matrix obtained by applying a random effect model with the function tssem1, and then analyze it with wls function to check it those results are the same to those obtained by applying tssem2 directly. With those two procedures I obtained differente results, even though they are suppose to be same.

Dear Mike,

I am sorry for bothering you again...but I have another question!

In the document attached (DATOS1.dat) I have six matrices. I did a cluster analysis in order to find some moderators (commands are attached in Fixed-cluster.R), dividing the data in two blocks : the first and second matrices are in one block, and the other four matrices in another. When I execute the first stage, it turned out that the second block (the fourth last matrices) are homogeneous (Chi-square=28.9735, df=26, p=.3123). Until here, everything seems correct.

Dear Mike,

I am having some problems when fitting a path model in the second stage (Random Effects Model) which includes some indirect effects. In the documents attached you can find the data (.dat), the commands I used (.R) and the path model I would like to fit (.png).

The error that appears is the next one:

Error in `$<-.data.frame`(`*tmp*`, "Std.Error", value = NA) :
replacement has 1 row, data has 0
In addition: Warning messages:
1: In pchisq(tT, df = dfT, lower.tail = FALSE) : NaNs produced
2: In sqrt(max((tT - dfT)/(n - 1), 0)/dfT) : NaNs produced
Warning message:

Hi Mike,

I am using random-effects MASEM and I would like to include a binary characteristic of the studies in my analysis. Based on your recent paper (Cheung, 2014), I know that mixed-effects model can be used to include study characteristics as the predictors in a MASEM model. However, I was wondering how I can do this using metaSEM codes. I could not find any metaSEM code example in your papers/website that explain how I should code and indicate the study characteristics in tssem1() and tssem2() functions in metaSEM.

Your help would be very much appreciated,

Thank you,
-- Hamed

Dear Mike,

I'm having some problems for installing metaSEM package...This error always appears, and I cannot find the solution:

install.packages("metaSEM")
Installing package into ‘D:/Documents/R/win-library/3.0’
(as ‘lib’ is unspecified)
Warning in install.packages :
package ‘metaSEM’ is not available (for R version 3.0.2)

Where could I find a new version of the package?

Thanks in advantage,

Kind regards.

Hi Mike,

In my stage two analysis I would like to impose equality constraints on some items' error variances in the S matrix to be consistent with the models from the original studies.

I wonder whether this is feasible at all, because here (http://courses.nus.edu.sg/course/psycwlm/Internet/metaSEM/masem.html) you wrote "Since we are conducting a correlation structure analysis, the error variances are not free parameters."

If it is possible, could you please provide a syntax example how to implement the equality constraints?