R. Jackson posted on Thursday, January 29, 2009 - 5:52 pm
This is a very basic question. I am having difficulties reading the MPlus output. I am unclear on what values are actually the path estimates. For example, I ran a CFA model with two continuous latent variables and 6 continuous observed variables. I created a visual model and want to add all of the path values and correlation values.
Under Model Results, I see the estimates column, but the estimates are all greater than 1. I don't think those would be the path coefficients. I used the STANDARDIZE output option and noticed under STDY Standardization, the estimates are all less than 1. Are those the values I should use? Thanks in advance.
The raw coefficients are given in the first column under Model Results. These coefficients can be greater than one. I believe that most people report standardized coefficients on path diagrams. In this case, report STDYX for continuous covariates and STDY for binary covariates. See Chapter 17 where the Mplus output is described.
WARNING: THE LATENT VARIABLE COVARIANCE MATRIX (PSI) IS NOT POSITIVE DEFINITE. THIS COULD INDICATE A NEGATIVE VARIANCE/RESIDUAL VARIANCE FOR A LATENT VARIABLE, A CORRELATION GREATER OR EQUAL TO ONE BETWEEN TWO LATENT VARIABLES, OR A LINEAR DEPENDENCY AMONG MORE THAN TWO LATENT VARIABLES. CHECK THE TECH4 OUTPUT FOR MORE INFORMATION. PROBLEM INVOLVING VARIABLE SMSM.
I am running a growth model that includes linear and quadratic terms, and i get the same error as above:
WARNING: THE LATENT VARIABLE COVARIANCE MATRIX (PSI) IS NOT POSITIVE DEFINITE. THIS COULD INDICATE A NEGATIVE VARIANCE/RESIDUAL VARIANCE FOR A LATENT VARIABLE, A CORRELATION GREATER OR EQUAL TO ONE BETWEEN TWO LATENT VARIABLES, OR A LINEAR DEPENDENCY AMONG MORE THAN TWO LATENT VARIABLES. CHECK THE TECH4 OUTPUT FOR MORE INFORMATION. PROBLEM INVOLVING VARIABLE S.
I looked at the tech4 output, and the correlation between i and s is greater than 1 (1.22). what does this mean and how do i address this issue?
I am creating latent factors using categorical variables. In the Standardized STDYX results two items have a correlation greater than one, however, in the Standardized STD results they correlate 0.391. Which should I be using?
Std gives a residual covariance. StdYX gives a residual correlation. If it is greater than one, the model is inadmissible.
QianLi Xue posted on Tuesday, November 09, 2010 - 1:16 pm
In the MPlus user's guide on Page 656, although the text says "The TECH4 option is used to request estimated means, covariances, and correlations for the latent variables int the model," the TECH 4 output includes variable X, which I assume is an observed variable. why is that?
Hello! I am running growth curve models and receive the "Latent covariance"...error message When I fix the slope to 0, and the quadratic when I have it in the model to 0, I no longer receive this message. When I look at the TECH4 output, the covariance matrix indeed shows that the S by S value is negative...so I can understand why I would need to fix it to 0. While this is ok for a single growth model, for the models that I have 2 growth models, this defeats the purpose of my analyses: to determine whether these processes covary over time....so that I was hoping to assess the correlation between the two correlations. Any thoughts on how to proceed? thanks!
Related to previous posts, I am running a SEM with both latent and observed variables. In the standardized solution of the structural model, a few of the path coefficients in are greater than 1. Looking in Tech 4, however, there are no correlations greater than 1. What am I missing here? I thought that the paths, in terms of standard deviations, have to be less than 1. Many thanks-