General SEM Discussions
diana
Joined: 04/17/2019
how to avoid NA in confidence interval
Hello, I often got NA in confidence interval when fitting univariate or bivariate SEM and changing optimizers didn't help. Here is the code of a bivariate ACE model, and the output when I use 'SLSQP' optimizer . I wonder how can I aviod NA when estimating CI of parameters and algebra. Thank you so much!
vars <-c('tea_5g','smk_num_4g')
covars <- c("age","region_type")
nv <- 2 # number of variables per twin
ncv <- 2 # number of covariates
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diana
Joined: 04/17/2019
the thresholds in SEM of ordinal variables
Hello, I have got a question about the thresholds in SEM of ordinal variables and really need your help.
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PaulTwin
Joined: 01/29/2017
Latent spline/piecewise regression model on cross sectional data
Hello,
For my research, I would like to estimate the association between two latent variables using a spline/piecewise regression model with a single knot. The model should estimate two separate linear regression lines and the knot location (see attached image).
The two latent variables are anxiety and negative affectivity and both are measured with 7 indicators on a 1-5 Likert Scale.
rranne2@uic.edu
Joined: 12/10/2018
Finding R-squared for two different models
Hello!
I have a question about how to calculate r-squared for two different kinds of models. One is correlational and the other models change over time, with just two time points. They both include latent constructs, with anxiety and depression in both models as latent variables derived from four items each. The models are identified and have a relatively good fit CFI of .944 and .954, respectively.
1) "Plan E" Correlational Model (attached visual)
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ZR
Joined: 07/26/2017
How are weights used in mxData
Hi,
I couldn't find a in depth enough explanation in the documentation and I don't know c++ to be able to get this information from the source code, but I just wondered if anyone can expalin exactly how the weights in the "weights" argument in mxData is actually used mathematically? I know obviously a bigger weight will give more weight to that row of data etc, but I wanted a more detailed explanation than this if that's possible?
Thanks!
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rranne2@uic.edu
Joined: 12/10/2018
links are down
I tried to use the link to learn more about Multiple Groups under the Features tab on this website, but the link was not active. It was not able to load the page. Is there a way to put that page up again or post that information somewhere on this website? Thanks!
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rranne2@uic.edu
Joined: 12/10/2018
multi group comparisons in RAM
Hello! I'm very new to R and OpenMx. I recently successfully ran a model I was interested in with a lot of pathways. The next step in my data analytic plan is to test whether the strength of all these pathways in this model are different for men and women. I was told I could use multi group analyses in order to test this. I planned on building an identical model for men and for women allowing gender to vary, and then constricting gender pathways to 1, and compare these two approaches. However, I haven't found any examples yet of someone who has done this.
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figureitout
Joined: 07/23/2018
Mplus and SPSS Training - London - SEM, multilevel, mediation/moderation, growth curves, Data Management/SPSS syntax
A series of one-day quantitative methods training courses to be held in Autumn/Winter 2018/2019,
in London
---------------
Tuesday 6 November 2018 - Structural Equation Modelling using Mplus
at LSE, London
An introductory course to CFA, SEM, and to using Mplus software
Wednesday 7 November 2018 - Testing for Mediation and Moderation using Mplus
at LSE, London
Learn to test mediation and moderation type models using Mplus
Veronica_echo
Joined: 02/23/2018
Need help to fit a piecewise latent growth curve with time-invariant covariates
Hi everyone,
I am trying to fit a PLGC model with TICs, but it reported errors. I am attaching data and codes I used for the model. I set the initial values as the estimations from Mplus8 (script is also attached, need to change to .inp). Any advice would be appreciated.
--solved, thanks
alha9497
Joined: 01/29/2018
Fitting SEMs from correlation matrices and standard errors
Hello,
I have two general questions and I am particularly interested in doing these models in OpenMx.
1. Is there a way to estimate SEMs with input only being pearson's correlations and the standard errors from the pearson correlations? I want to do this without back transforming to the sample size, so essentially the sample size is unknown.