I have a question similar to the previous poster. I'm doing a multiple group analysis and I want to test the noninvariance of a particular path coefficient. Do I need to label the coefficient in the overall model command? My input is below:
MODEL: st BY svs1-svs8; scientid by atmr sdcr sciid; tapp BY newagq1 newagq4 newagq7; sapp by newagq2 newagq5 newagq8;
tapp on scientid st; sapp on scientid st; scientid on st;
MODEL INDIRECT: tapp ind scientid st; sapp ind scientid st;
Model other: scientid on st(a); Model science: scientid on st(b);
I have run a multigroup latent growth model and am trying to compare the two groups for significant differences in the mean and variance of the two latent factors. Using the code below (I have also tested an alternative form of the MODEL TEST command, where p1=p21, and so on) produces a Wald test with a very low, significant, p-value for the omnibus test of all four parameters. However, when I examine each parameter one-by-one, none of them show a significant difference between groups.
Model Group 1: [int] (p1); [slope] (p2); int (p3); slope (p4);
Model Group 2: [int] (p21); [slope] (p22); int (p23); slope (p24);
Can you tell me if I am doing anything wrong? It seems odd that none of the individual parameters are close to significance while the omnibus test is significant - I am not sure how one would report this in a useful fashion, since no specific difference between the two groups can be identified.
I have searched the forum archives for an answer, but haven't seen this described before - apologies if I have overlooked anything. Thank you.
The joint test has more power to reject than each individual test so the outcome is quite possible. You can try to use a likelihood-ratio chi-2 difference test instead of the Wald test to check if you get the same result.
Pia H. posted on Thursday, October 06, 2016 - 1:02 am
Dear Prof Muthén
I want to compare regression coefficients of latent (interaction) variables between two groups using the model test command, but I get an error message in my output:
We need to see the full output - send to Support along with your license number.
Qiong Wu posted on Thursday, June 15, 2017 - 9:41 pm
I'd like to follow up with the discussion where you suggested "The joint test has more power to reject than each individual test so the outcome is quite possible. You can try to use a likelihood-ratio chi-2 difference test instead of the Wald test to check if you get the same result." I am testing the difference of mediation between two groups. The joint test had more power than individual tests about a1b11 - a2b12, a1b21 - a2b22. What is the syntax to use a likelihood-ratio chi-2 difference test instead of the Wald test?
MODEL constraint: new(a1b11 a1b21 a2b12 a2b22); a1b11=a1*b11; a1b21=a1*b21; a2b12=a2*b12; a2b22=a2*b22;
I also have another question on Wald's test: I am using MLR in my analysis, and I am wondering if Wald's test does produce a corrected Chi-square (adjusted by scaling correction factor), or is it uncorrected ML-based chi-square? Thank you so much for your responses!