Dear Andre, > -----Original Message----- > From: Andr� TavaresCorr�a Dias [mailto:[EMAIL PROTECTED] > Sent: Thursday, March 10, 2005 6:14 AM > To: John Fox > Cc: [email protected] > Subject: RE: [R] Structural equation models with R > > Dear John, > Thanks very much! I don�t know how I didn�t see this before. > I checked a thousand of times�
(Recall that there was a typo in Andre's model specification.) > There is one more thing that I > can not understand. What are the possible reasons for > problems on calculation of confidence interval for RMSEA? For > the same model I sent before (after correction of the > variable name) the lower CI output was NA: > > Model Chisquare = 10.824 Df = 13 Pr(>Chisq) = 0.62558 > Goodness-of-fit index = 0.91656 > Adjusted goodness-of-fit index = 0.76895 > RMSEA index = 0 90 % CI: (NA, 0.15652) > BIC = -60.425 > > I have other models with the same behavior, even when the > estimative of RMSEA is different from zero. > > Model Chisquare = 15.165 Df = 14 Pr(>Chisq) = 0.367 > Goodness-of-fit index = 0.89038 > Adjusted goodness-of-fit index = 0.71811 > RMSEA index = 0.053558 90 % CI: (NA, 0.19141) > BIC = -61.564 > The method used to get the confidence interval (from Browne and Du Toit, Multivariate Behavioral Research, 1992, 27:269-300) can produce a lower bound above the RMSEA estimate or an upper bound below the estimate; when this happens, the bound is set to NA. One of the nice things about R is that you can look at the code for a function -- in this case, summary.sem() -- to see exactly what it does. Take a look at how RMSEA.L and RMSEA.U are computed. Regards, John ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
