Third Party Software
jbauer
Joined: 04/14/2014
Effects from TSSEM larger than in original studies
Hi Mike,
many thanks for the fantastic metaSEM package! I used it to combine models from two original studies.
(1) What astonishes me is that some of the structural parameters estimates from TSSEM Stage 2 are even larger than the ones from the individual studies (e.g. study 1: beta = -.40; study two: beta = -.53; TSSEM2: beta = -.66). Naively I had expected that the comnbined TSSEM2 etimates should be somewhere between the ones of the original studies. I am wondering how this is possible. Can I trust this finding?
Ryan
Joined: 02/08/2014
accumulative sample size
Dear Mike,
Is there an approach to compute the accumulative sample size (N)?
It is quite convenient to know the number of primary studies (n) by "pattern.na ( )", but I can't find a syntax for the accumulative sample size (N).
Thanks in advance!
Ryan
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mdr
Joined: 02/12/2014
Variance calculations in Onyx
I've been trying to match the variances reported by Onyx with those reported by AMOS. Following the example in the AMOS User Guide, I've created a model with four observed variables (recall1, recall2, place1, place2 in the file Attg_yng.xls file) connected to each other with double-headed arrows to determine the covariances of the variables, as is done in AMOS.
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Ryan
Joined: 02/08/2014
An error in stage-1 for fixed model
Dear Mike,
I encounter a problem when trying the fixed model for stage 1. The error info is
"Error in if (!all(isPD)) stop(paste("Group ", (1:no.groups)[!isPD], " is not positive definite.", :
missing value where TRUE/FALSE needed".
The dataset is exactly the same one I used in random model. I tried "fixed1<-tssem1(my.df, n, method="FEM", no.string="NA")", and NA is the expression in my dataset for missing values, but metaSEM seems not to accept this argument.
Would you please provide any hints?
Thanks!
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Ryan
Joined: 02/08/2014
Increasing the number of replication from default(50) to 5000
Dear Mike,
When I call summary (random2a, R=5000), z-values and standard errors of some estimates are significantly changed. The estimates and goodness-of-fit indices remain the same.
I didn't try (R=10000), as "R=5000" already took 7 hours to finish;)
However, if the number of replications dramatically influences the z-values and std.errors, are there any criteria for choosing one result for reporting?
Thanks!
Ryan
Ryan
Joined: 02/08/2014
TSSEM_stage2_output:(1)inconsistent results,(2)unsatisfactory CFI & TLI
Dear Mike,
After struggling with my data in the stage 1 of TSSEM, I finally moved into the stage 2. However, the output seems not to be very good.
(1) The results of two approaches of specifying models are different.
Specifically, when using "diag.constraints=TRUE, intervals.type="z"", the result suggests "Amatrix[1,22]" and "Amatrix[1,23]" are significant. But removing the "constraints" and "intervals.type", the result suggests "Amatrix[1,21]" is significant.
In addition, both results have same goodness-of-fit values. Which result I should believe?
nickz
Joined: 10/02/2013
Model specification (fix factor loading or latent variable variance).
Hello All,
As the title suggests, I have a question regarding whether to fix the factor loading or the latent variable variance. Both can be fixed in order to derive a 'scale' for your latent variables. The fit statistics should be the same in both cases.
Ryan
Joined: 02/08/2014
"x is not positive definite"
Hi all,
I encounter a problem of "x is not positive definite" when using Cheung's Two-stage MASEM. Could anyone provide some clues?
I attach part of my dataset as samples. My R-syntax is "random1<-tssem1(entrymode,samplesize,method="REM",RE.type="Diag")" . This command ends with an error information:
Error in (function(x, n, cor.analysis = TRUE, dropNA = FALSE, as.matrix = TRUE), : x is not positive definite!
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mdr
Joined: 02/12/2014
Overspecified model
Hi,
I'm new to both SEM and Onyx as my question probably shows.
An SEM model that I've specified with Onyx has the symbol with an exclamation mark displayed, and the associated message tells me that the model is overspecified.
Onyx FAQs notes, "If you obtain this error, you have most likely included more freely estimated parameters in your model than there are observed statistics. Try to fix freely estimated parameters or remove paths."
However, Onyx's Estimate Summary reads:
Observed Statistics : 65.0
estimated Parameters : 24
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cuttance
Joined: 01/20/2014
Onyx for producing R scripts
Is the an equivalent to Onyx for diagramatically producing R code for data preparation, such as recoding data, creating new variables, matching/merging datasets, etc?
Peter
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