Message/Author |
|
|
Can you tell me how to impose equality constraints on the mean growth parameters in a 2 part growth model? I'm using the KNOWNCLASS command to specify my 3 groups. An unconstrained model shows that the slopes for both the binary and continuous parts of the outcome variable vary across groups, but I would like to be able to test whether these differences are significant. Thanks. |
|
|
Equality constraints are imposed by placing the same number in parentheses behind two or more parameters. See the user's guide for more information. I do not think testing the equality of these two means would make sense given that one growth model is based on logistic regression and one linear regression. |
|
|
Hi Linda, Thanks for your response. I wasn't clear - what I want to do is test equality of the slopes for the continuous part across groups, and then for the binary part across groups. I don't want compare the 2 slopes to each other. I have checked the manual, but can't seem to figure out how to impose the cross group equality constraints in this setting. Can you recommend an example I can look at for imposing across group equality constraints on su and sy as defined in the code below? Thanks. classes= tx(3); knownclass=tx (group=1 group=2 group=3); data twopart: names = lbinge1-lbinge6; binary = ubinge1-ubinge6; continuous = ybinge1-ybinge6; model: %overall% iu su | ubinge1@0 ubinge2@.25 ubinge3@.5 ubinge4@1 ubinge5@1.5 ubinge6@2; iy sy | ybinge1@0 ybinge2@.25 ybinge3@.5 ybinge4@1 ybinge5@1.5 ybinge6@2; su@0; iu with su@0; iu with sy@0; su with iy-sy@0; |
|
|
The means of the slope growth factors are referred to in brackets. Equality constraints are specified by placing the same number in parenthesis after the parameters that are held equal. [su] (1); [sy] (2); If you continue to have problems, send your input, data, output, and license number to support@statmodel.com. |
|
Back to top |