multi-group WLS
Posted on
pascofearon
Joined: 05/07/2013
| Attachment | Size |
|---|---|
| Lavaan twin modelling[1].R | 1.51 KB |
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Hi Mike,
Hope this finds you well. I'm trying to run a multi-group SEM (twin data) using summary statistics rather than raw data. I have the covariance and asymptotic covariance matrices. I think I'm hitting errors in the way I'm handling the multi-group aspect - as WLS says the following:
Error in withCallingHandlers(expr, warning = function(w) invokeRestart("muffleWarning")) :
(list) object cannot be coerced to type 'double'
I've supplied the two matrices as lists - one for each group. The script is attached.
I also get this message:
In addition: Warning message:
In if (is.pd(Cov)) { :
the condition has length > 1 and only the first element will be used
Any help much appreciated as always!
Best,
Pasco
Dear Pasco,
Dear Pasco,
Attached is the code for your model.
You may note that the SEs in lavaan are different than those in OpenMx as the precision of the inputs is different in these two cases.
Best,
Mike
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In reply to Dear Pasco, by Mike Cheung
Multi-group WLS
Thanks so much Mike - that's fantastic. I was quite far off in my attempt here!
All best,
Pasco
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WLS follow-up
Hi Mike,
I have a follow-up query about this - the model runs perfectly with your edits, and returns sensible looking parameter estimates and standard errors. However, when I add a request for confidence intervals I get very strange estimates. I'm not sure if my code is wrong, or there is a more fundamental issue with the likelihood-based intervals. The adjusted part of the code was just:
ace <- mxModel('All', gp1, gp2,
mxFitFunctionMultigroup(c('gp1.fitfunction', 'gp2.fitfunction')), mxCI(c('gp1.Amatrix'), interval = 0.95, type=c('both')))
fit1 <- mxRun(ace, intervals = TRUE)
Thanks for any help, as always!
Best,
Pasco
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Dear Pasco,
Dear Pasco,
The parameter estimates with the LBCI are the same as those without the LBCI.
The model without the LBCI:
free parameters:
name matrix row col Estimate Std.Error A
1 a gp1.Amatrix P1 A1 0.87909044 0.110115
2 c gp1.Amatrix P1 C1 0.02645751 2.585079
The model with the LBCI:
free parameters:
name matrix row col Estimate Std.Error A
1 a gp1.Amatrix P1 A1 0.87909044 0.110115
2 c gp1.Amatrix P1 C1 0.02645751 2.585079
confidence intervals:
lbound estimate ubound note
a -0.9487976 0.87909044 0.9488027
c -0.5184616 0.02645751 0.5184611
Could you tell us what the issues are?
Best,
Mike
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In reply to Dear Pasco, by Mike Cheung
Hi Mike,
Hi Mike,
Yes the estimates are fine, but it's the CIs - they run almost from -1 to 1 (for a).
Best,
Pasco
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In reply to Hi Mike, by pascofearon
sign indeterminacy?
I bet some of your free parameters are sign-indeterminate.
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In reply to sign indeterminacy? by AdminRobK
Ahhh, of course - thanks,
Ahhh, of course - thanks, that's likely it!
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