Message/Author 

Enis Dogan posted on Friday, August 17, 2007  3:43 pm



Trying to confirm factorial invariance (1 factor only) across 2 groups; observed are 6 item bundles (assumed continous). I ran the model with the following constraints (1)equal factor loadings; (2) equal (factor loadings + variance/residuals). Do you i need to run an unconstraint model to test if (1) and (2) fit the data no worse in order to be able to test the hytpothesis of factorial invariance? If yes; how do i run an unconstraint model? Do I a) Combine the two groups and, get rid of grouping variable, run the 1 factor CFA. b) Run the 1 factor CFA for each group separately and add chisquare and df from each I hope i got the syntax for (1) and (2) right: (1): DATA: FILE IS data.dat; VARIABLE: NAMES ARE group bundle1bundle6; GROUPING = group (0= g1 1=g2); ANALYSIS: TYPE = mgroup ; MODEL: f1 BY bundle1bundle6; OUTPUT: standardized ; (2): DATA: FILE IS data.dat; VARIABLE: NAMES ARE group bundle1bundle6; GROUPING = group (0= g1 1=g2); ANALYSIS: TYPE = mgroup ; MODEL: f1 BY bundle1bundle6; f1 (1) bundle1 (2) bundle2 (3) bundle3 (4) bundle4 (5) bundle5 (6) bundle6 (7) ; OUTPUT: standardized ; 


A convenient way to do invariance testing is to do a 2group analysis following the suggestions in the UG chapter in the section called "Testing for Measurement Invariance..." Note that the first factor loading is fixed at 1 as the default so this parameter should not be referred to. 


This is in Chapter 13 of the user's guide after the discussion of multiple group modeling. 

Enis Dogan posted on Monday, August 20, 2007  12:21 pm



That was helpful. Thank you. I am still having rouble running the baseline model (configural invariance only). syntax looks like this: DATA: FILE IS data.dat; VARIABLE: NAMES ARE booklet bundle1bundle4 bundle6 bundle7; GROUPING = booklet (0= book1 1=book2); ANALYSIS: TYPE = mgroup ; MODEL: f1 BY bundle1bundle4 bundle6 bundle7; MODEL book2: f1 BY bundle1bundle4 bundle6 bundle7; OUTPUT: standardized ; The error message i get reads: THE STANDARD ERRORS OF THE MODEL PARAMETER ESTIMATES COULD NOT BE COMPUTED. THE MODEL MAY NOT BE IDENTIFIED. CHECK YOUR MODEL. PROBLEM INVOLVING PARAMETER 25. Does the syntax look OK? i also tried to run the same, this time by fixing the mean of the latent variable at zero. i am getting the same error message again: DATA: FILE IS data.dat; VARIABLE: NAMES ARE booklet bundle1bundle4 bundle6 bundle7; GROUPING = booklet (0= book1 1=book2); ANALYSIS: TYPE = mgroup ; MODEL: f1 BY bundle1bundle4 bundle6 bundle7; [f1@0]; MODEL book2: f1 BY bundle1bundle4 bundle6 bundle7; [f1@0]; OUTPUT: standardized ; 


The problem is that you are freeing the first factor loading by mentioning it in the groupspecific MODEL command. Instead of MODEL book2: f1 BY bundle1bundle4 bundle6 bundle7; try MODEL book2: f1 BY bundle2bundle4 bundle6 bundle7; 

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