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No user picture. diana Joined: 04/17/2019

how to avoid NA in confidence interval

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General SEM Discussions
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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No user picture. diana Joined: 04/17/2019

the thresholds in SEM of ordinal variables

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General SEM Discussions
Hello, I have got a question about the thresholds in SEM of ordinal variables and really need your help.

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Picture of user. PaulTwin Joined: 01/29/2017

Latent spline/piecewise regression model on cross sectional data

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General SEM Discussions
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.

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No user picture. rranne2@uic.edu Joined: 12/10/2018

Finding R-squared for two different models

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General SEM Discussions
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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No user picture. ZR Joined: 07/26/2017

How are weights used in mxData

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General SEM Discussions
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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No user picture. rranne2@uic.edu Joined: 12/10/2018

links are down

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General SEM Discussions
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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No user picture. rranne2@uic.edu Joined: 12/10/2018

multi group comparisons in RAM

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General SEM Discussions
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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No user picture. figureitout Joined: 07/23/2018

Mplus and SPSS Training - London - SEM, multilevel, mediation/moderation, growth curves, Data Management/SPSS syntax

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General SEM Discussions
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

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No user picture. Veronica_echo Joined: 02/23/2018

Need help to fit a piecewise latent growth curve with time-invariant covariates

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General SEM Discussions
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

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No user picture. alha9497 Joined: 01/29/2018

Fitting SEMs from correlation matrices and standard errors

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General SEM Discussions
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.

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