Dear Antonio, > -----Original Message----- > From: Antonio Prioglio [mailto:[EMAIL PROTECTED] > Sent: Tuesday, July 13, 2004 5:54 PM > To: John Fox > Cc: [EMAIL PROTECTED] > Subject: RE: [R] Help with factanal and missing values > > On Tue, 13 Jul 2004, John Fox wrote: > > > Dear Antonio, > > > > This example is (as stated) a second-order CFI, where each of the > > primary factors, F1, F2, and F3 depends upon the > second-order factor > > F4. To have no second-order structure, simply define variances and > > (assuming that you're specifying correlated factors) > covariances among > > the factors. For the Thurstone example, these would be, in > addition to > > the variances already set to 1, F1 <-> F2, F1 <-> F3, and F2 <-> F3. > > Ok I understand the second order part in relation to F4. > > I'm afraid I'm a bit slow on the last part. > > "Fn <-> Fn NA 1" is the variance for the factor n.
Yes. This is set to 1, standardizing the factors, which is conventional. > "Fn -> Item.a lam.z NA" is the grouping of the items to each factor These (i.e., the lambdas) are conventionally called factor loadings. > "Fn <-> Fm gam.w NA" I take is the covariance among factors. > Yes, though it is unconventional to use gamma to represent a covariance (a correlation, since the factors are presumably standardized) in factor analysis. > Is this correct? Do I need to set variances for each item > (Item.a <-> Item.a)? > Yes. These *error* variances, which should be free parameters, are conventionally called uniquenesses in factor analysis. As a general matter, it would help, I think, to look more carefully at the example, since it includes factor loadings and uniquenesses. If you haven't already done so, you might also look at the appendix on structural-equation models to my R and S-PLUS Companion, which is at <http://socserv.socsci.mcmaster.ca/jfox/Books/Companion/appendix-sems.pdf>. This appendix doesn't include a CFA example, but it does explain how to prepare input to the sem() function. Regards, John > Saluti, > Antonio Prioglio > > -- > We are what we repeatedly do. Excellence, then, is not an > act, but a habit. > Aristoteles > > > /"\ > \ / ASCII RIBBON CAMPAIGN - AGAINST HTML MAIL > X - AGAINST MS ATTACHMENTS > / \ > > http://www.gnu.org/philosophy/no-word-attachments.html > > ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html