We have a weighted sample, weighted as follows: The sampling was carried out in four strata, with sampling probabilities .37, .48, .70 and 0.89, respectively. We want to carry out a nonlinear regression analysis. In SPSS ans Stata, this seems to be possible only for nonweighted samples.
1. Is nonlinear regression possible in Mplus?
2. If yes, can this be done with our weighted sample?
The reference to UG ex 3.18 and also "Mediation" seem to relate to the standard parametrization of interaction, which is not difficult. Our problem is statistical inference for C in the reparametrized model. This requires use of the nonlinear regression equation we stated first:
Thanks to Linda Muthen for pointing out in an email to me that the results provided in the Mplus output are correct. I had mistakenly computed an approximate c.i. as estimate +- 2SE, while Mplus provides a c.i. using estimate +-1.96SE.
"We are particularly interested in the estimate and confidence interval for C, which is the X1-value where the regression lines for D=0 and D=1 cross. (The model is eqn 15 in the ref below.)
Widaman, K.F., Helm, J.L., Castro-Schilo, L., Pluess, M., Stallings, M.C., & Belsky, J. 2012. Distinguishing ordinal and disordinal interactions. Psychol.Methods, 17, (4) 615-622"
My colleague Lydersen succeeded in testing this by computing the interaction term in SPSS and then using the model constraints function.
I want to perform the same test, but I use latent variables, so I am not able to compute an interaction term in SPSS to use in the model. I also use the grouping function (Satorra-Bentler)to test for moderation and not the xwith.
So, my question is: Is it possible to do this test in Mplus using latent variables and the grouping function?
If yes, I would be very grateful for a description on how to perform this test.