LTA and odds ratio question
Message/Author
 Jessica Larsen posted on Wednesday, May 08, 2013 - 11:08 am
I am conducting a Latent Transition Analysis (LTA) in Mplus and using a covariate to examine the interaction of the covariate on the transition patterns. My sample is a clinical sample, and I am examining transitions over the course of treatment. My covariates represent categories with low base-rates (i.e. males who report past sexual abuse). What I am finding, is that when the covariate is included in my model, certain transition paths (ie c1#2 to c2#3) are estimated to have 0 probabilities. This is of substantive interest and makes sense theoretically. However, statistically, this zero estimate causes one of my estimated odds ratios to be very large (i.e. 57725). Is this accurate? How can I report this in my write-up?
 Linda K. Muthen posted on Thursday, May 09, 2013 - 9:47 am
I would have an asterisk in the table and say something like:

Odds rations cannot be computed because of a perfect correlation.
 JuliaSchmid posted on Wednesday, February 06, 2019 - 12:20 am
Hi Linda

I run a LTA and I would like to report Odds instead of Transitional probabilities. Do I have to calculate them (CI included) by hand or is there a possibility that Mplus give it in the output?

Thank you for your help,
Julia
 Bengt O. Muthen posted on Wednesday, February 06, 2019 - 5:22 pm
You can express them in Model Constraint using parameter labels given in the Model command. Then you get CIs too.
 JuliaSchmid posted on Thursday, February 07, 2019 - 7:44 am
Hi Bengt!

I would appreciate, if you would explain the procedure in more detail: How can I calculate the Odds Ratio exactly via Model Constraint-Command?

Let's say I run a LTA with two measurement points and 4 classes each. An my class indicators/variables are:

Steuko_1 Befreg_1 Selko_1
Steuko_2 Befreg_2 Selko_2

 Bengt O. Muthen posted on Thursday, February 07, 2019 - 5:28 pm
I assume your variables are binary.

See our Short Course Topic 6, slides 48 and on.
 JuliaSchmid posted on Friday, February 08, 2019 - 5:50 am
Perfect, thanks to the sliedes, I understand now the logic of the input.
No, my variables are contiuous - I run a LPTA. Does this fact change the procedure mentioned on slides 48f?
 Bengt O. Muthen posted on Friday, February 08, 2019 - 7:04 am
Not if the odds ratios you mention refer to only the transitions, not the outcomes. See web note 13 which describes such odds ratios:

Muthén, B. & Asparouhov, T. (2011). LTA in Mplus: Transition probabilities influenced by covariates. Mplus Web Notes: No. 13. July 27, 2011.