Constraining slopes to equality PreviousNext
Mplus Discussion > Growth Modeling of Longitudinal Data >
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 Natalie Wright posted on Wednesday, September 25, 2013 - 1:58 pm
Hi,
In a latent growth model with 2 variables each measured at 3 timepoints, is it possible to constrain the slope values to be equal between the two variables? Iím interested in evaluating whether the rate of change is different for the 2 variables in my model, so to test this I would like to compare the fit of a model with the constrained slopes to the fit of a model with unconstrained slopes.

Thanks for your help!
 Linda K. Muthen posted on Wednesday, September 25, 2013 - 3:24 pm
Yes, this can be done.

i1 s1 | y1@0 y2@1 y3@2;

i2 s2 | z1@0 z2@1 z3@2;

[s1] (1);
[s2] (1);

holds the means of the slope growth factors equal.

s1 (2);
s2 (2);

holds the variances of the slope growth factors equal.
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