Changing the reference group PreviousNext
Mplus Discussion > Latent Variable Mixture Modeling >
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 Anonymous posted on Saturday, January 08, 2005 - 4:05 pm
I am doing a latent mixture model with 4 classes, defined by 3 measures. In order to look at the differences between classes, I need to change the reference group (class 4). I have tried to enter in the estimates after each class statement, but it seems to be a trial and error process. In fact it seems as if what you put under class 1 determines the order of the rest of the classes. So, I am unsure how to make class 4 the class I want it to be. Any suggesstions would be helpful.
 bmuthen posted on Saturday, January 08, 2005 - 4:11 pm
The last class often has the largest or smallest thresholds - corresponding to small or large probabilities of item endorsement. So giving high or low starting values for the class 4 thresholds often works.
 Andrea Mata posted on Wednesday, April 16, 2008 - 10:33 pm
I am running a four class LCGA model with 9 covariates (6 dichotomous, 3 continous), but I want to change the reference class to a specific latent class instead of the last class. I have written this syntax command: %c#3% underneath the c on "list of all of the covariates" command. However, I do not think it changed the reference group to be class number 3. And if it did, how would I know if it did? Is this the correct syntax? I guess my question is: how do I change the reference group in a conditional LCGA model?
 Linda K. Muthen posted on Wednesday, April 16, 2008 - 11:12 pm
You change the reference class by using the estimated parameter values for the class you want to be last as starting values for the last class.
 Johannes Bauer posted on Wednesday, March 16, 2011 - 9:08 pm
I am running a latent profile analysis with three latent profiles and covariates. I am trying to make class 1 the reference group by specifying it as group 3 and starting values as follows:

%grp#1%
[F20_32*-0.809 F20_23*0.100];
%grp#2%
[F20_32*0.328 F20_23*0.472];
%grp#3%
[F20_32*0.259 F20_23*-0.457];

However, group 3 keeps coming out as class 2. What could I do to fix this?
 Bengt O. Muthen posted on Wednesday, March 16, 2011 - 9:35 pm
You can also give starting values for other parameters, for instance

[c#1*? c#2*?]
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