Output for theta and delta parameteri... PreviousNext
Mplus Discussion > Categorical Data Modeling >
 Richard T. Campbell posted on Wednesday, March 22, 2017 - 2:57 pm
I ran example 3.13 which uses WLMV with the theta parameterization. The output shows scale factors for the endogenous variables. When I change to the delta I see residual variances. I think I understand the distinction between the two, but I am puzzled by the output which seems to contradict the explanation in the user manual.
 Bengt O. Muthen posted on Wednesday, March 22, 2017 - 7:04 pm
Are you adding to the output requests for 3.13?

Could you send the output for your run to Support?
 James Algina posted on Saturday, April 08, 2017 - 7:42 pm

If the theta parameterization is used in a two-group one-factor factor model and the scalar model is believed to be an adequate model for the data, is the following correct? The expressions from page 495 in the Mplus manual
P (u = 0 | x) = F (t1 - b*x),
P (u = 1 | x) = F (t2 - b*x) - F (t1 - b*x),
P (u = 2 | x) = F (- t2 + b*x),
with b = the factor loading and x = the factor, can be used to calculate category probabilities on item i for the group in which the residual variance equals one, but have to be modified for the other group by dividing each term by the residual standard deviation for item i.

 Bengt O. Muthen posted on Monday, April 10, 2017 - 7:08 pm
These formulas are ok if you want the probabilities conditional on specific factor values x.
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