Tools for Those Who Summarize the Evidence Base
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Hello Mike and others;
I am trying to conduct random-effects TSSEM on a dataset of 61 studies (data set, "hamed.dat", is attached), using metaSEM 0.9.6, Openmx 2.3.1, and R 3.2.2 (2015-08-14). However, I am stuck in stage 1 of the random-effects analysis with error code "6". I even changed the default optimizer in Openmx from "SLSQP" to "NPSOL", but no luck. Regardless of changes I make to my data, it seems that I can not produce error code "0" or "1" in stage 1 of random-effects TSSEM. This is while the eigen values for the pooled correlation matrix are all positive and the matrix is actually positive definite.
I have attached the RScript that I am using for this analysis.
Any help will be greatly appreciated.
Thank you,
/Hamed
Tags:
Hi Hamed,
There is only 1 study in many of these cells. It is not possible to estimate the heterogeneity variances.
Regards,
Mike
pattern.na(MASEM$Data, show.na = FALSE)
x1 x2 x3 x4 x5 x6 x7 x8 x9
x1 4 2 1 1 1 4 4 1 1
x2 2 29 10 14 15 7 15 1 3
x3 1 10 14 5 5 5 7 1 1
x4 1 14 5 27 12 3 16 5 3
x5 1 15 5 12 29 8 23 4 2
x6 4 7 5 3 8 14 9 4 2
x7 4 15 7 16 23 9 33 6 6
x8 1 1 1 5 4 4 6 19 13
x9 1 3 1 3 2 2 6 13 18
Thank you very much, Mike.
So, if I use the resulted pooled correlation matrix in stage 2 of TSSEM, does it mean that for the data points with one study, the correlation will be used as a covariance toward estimating the structural model?
If there is only 1 study, that correlation will be used in fitting the structural model. It is then difficult to call it a "meta-analysis" as there is only 1 study.
Mike
Thank you, Mike! I see the limitation.
Dear Mike and other users,
I am encountering the same problem. I have a smaller sample of 15 studies with a 5-variable matrix (1 binary variable, 4 continuous variables), but all 15 studies contribute data to every cell. Every study matrix is positive definite--is.pd(vector) gives TRUE for every study matrix. I get OpenMx status=6 when I run tssem1(vector, n, method="REM", RE.type="Diag"). When I rerun tssem1, I still get OpenMx status=6.
1. Within each study matrix, the correlations are sometimes based on different n due to missing data for certain variables within each study. Is this causing the problem?
2. What should I do to improve the optimization? I have run tssem1 on smaller datasets with 5 studies and similar 5-variable matrix and the first run of tssem1 gives OpenMx status=5 or 6, but after rerunning the OpenMx = 0.
3. For the 15-study dataset with tssem1 OpenMx status=6, if I run tssem2, OpenMx status=0. Can I interpret this result, and what caveats should I note given that the tssem1 had optimization problems?
Thank you in advance for your help!
Mei Yi
Dear Mei Yi,
Could you email me the data and R code so that I can check it?
Best,
Mike
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