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I have run across several cases where the pvalues given in the output do not always match what I obtain when I use DIFFTEST (in the case of WLSMV), or with the corrected chisquare difference test (in the case of MLR). In many cases this happens with twin models, but not always (sometimes with growth or SEM). I'm wondering why this would happen and which pvalues I should trust. 


I don't see why DIFFTEST or chisquare difference tests should give the same p values as any given H0 model. The H0 model is tested against a completely unrestricted H1 model, whereas difference testing typically uses a more specific H1 model  a model that is just a little bit more general than H0. Maybe I am misunderstanding your question. 


Hi. Sorry I was unclear. The pvalues I am referring to are for a particular parameter, not the overall model fit. So, in my specific case, I am running an ACE model, and the output ztest for the C loading suggests it is highly significant, but setting this loading to zero results in a nonsignificant DIFFTEST result. 


The C component may be near the 0 boundary  in that case the SE is not reliable and the Difftest is probably better. 


Unfortunately I don't think that's it, because actually, the C loading is .563, SE=.191, p=.003. But the DIFFTEST (df=1) is 2.172, p=.1406. 


Then you need to send the relevant files and your license number to support@statmodel.com. There is not sufficient information to answer this question. 

Yvan posted on Friday, July 06, 2012  6:49 am



Dear all, I am running following model: missing = all (99); ANALYSIS: Estimator = MLR; Type = General; MODEL: f1 BY SW3 SW4; f2 BY .... f8 ON f2 f6; f2 ON ... Output: SAMPSTAT MODINDICES (0) STANDARDIZED RESIDUAL TECH1 TECH2 TECH3 TECH4 TECH5 FSCOEF FSDET CINTERVAL PATTERNS; but I do not get the twotailed pvalue...I get Estimates S.E. Est./S.E. Std StdYX. Is this normal? Or what is my mistake? Thank you so much for your help. I am appreciate this. Regards 


With WLSMV we do not give standard errors for standardized coefficients when the model includes covariates. 

Yvan posted on Monday, July 09, 2012  12:41 am



Dear Mrs Prof Muthen, thank you so much for you fast and helpful answer. 

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