Message/Author 

Linda Bode posted on Friday, July 30, 2010  4:20 am



Hi! For my Master thesis I have to test my data for measurememt invariance since I am comparing four countries with about 50 respondents each. Unfortunately, I never learned another program than SPSS and therefore I am trying to figure out how MPLUS works by myself. I read the User guide and the handouts, but I am still not sure how to do it. I wanted to start with a simple CFA for each country, but the program shows me the following Error warning: One or more variables have a variance of zero. check your data and format statement. I dont have any missing values in my data set, I checked it twice with SPSS. This is my syntax in short (I have five more factors): TITLE: CFA; DATA: FILE IS "... CFA.dat"; VARIABLE: NAMES ARE a1 a2 a3 b1 b2 b3 c1 c2 c3 d1 d2 d3 e1 e2 e3 f1 f2 f3 g1 g2 h1 h2 h3; ANALYSIS: ESTIMATOR IS ML; MODEL: A BY a1 a2 a3; B BY b1 b2 b3; C BY c1 c2 c3; D BY d1 d2 d3; E BY e1 e2 e3; F BY f1 f2 f3; G BY g1 g2; H BY h1 h2 h3; OUTPUT: standardized; I am not sure if i did it correct, I tried to work with examples i found on the internet. I hope someone can help me. Thanx 


It sounds like you are setting up the reading of your data incorrectly. Please send the input, data, output, and your license number to support@statmodel.com. 

Linda Bode posted on Friday, July 30, 2010  11:54 am



I am so sorry, I found the mistake. I actually had one missing value, not sure why SPSS could not find it. I would like to make sure that I test for measurement invariance the right way: (1) I am running a CFA in each country separately, hoping that the model fit is sufficient in each country. What is the easiest was to test for configural, metric and scalar invariance? Do I have to write a syntax for each country separately again or do I have one syntax including all countries? Sorry for these very basic questions and thanks a lot for your help. 


See the Topic 1 course handout under multiple group analysis. 

Linda Bode posted on Wednesday, August 04, 2010  2:04 am



One last question: Is there a rule of thumb about the required sample size to test for measurement invariance? And do you know a reference where I can read more about it? Thanx a lot! 


I know of no rule of thumb for sample size. It depends on the model and the quality of the variables. You would need to do a Monte Carlo simulation study to understand the sample size needed for your particular study. 

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