Thresholds
Message/Author
 shawna anderson posted on Wednesday, March 02, 2005 - 6:22 pm
Hi--I'm just wondering what exactly a threshold is, and how to determine how many a particular categorical variable has. Thanks!
 Linda K. Muthen posted on Wednesday, March 02, 2005 - 6:32 pm
The number of thresholds is the number of categories minus one. Thresholds are z scores such that a threshold has to be exceeded for a person to be in a particular category.
 shawna anderson posted on Thursday, March 03, 2005 - 1:38 pm
Hi again! I've run into some identification problems on a multi-group CFA. I've got three indicators of one latent variable. Bollen suggests that one way of achieving identification is to constrain the mean of the latent variable to be equal to the intercept of one of the indicators; I don't want to do this, since I'm interested in comparing the means of the latent variable across groups.
So...can I constrain the thresholds of these indicators to be equal across groups to achieve identification? What kind of consequences are there to doing this?
I guess my basic question is: what do you recommend?
Thanks so much for all your help!
 Linda K. Muthen posted on Thursday, March 03, 2005 - 3:34 pm
I would have to see your output to see why you are having identification problems. You would need to send it along with your license number to support@statmodel.com.
 Sarah Ryan posted on Tuesday, September 20, 2011 - 2:13 pm
I am modeling an SEM model with several LF's, all with observed ordinal or binary indicators, and an ordinal outcome using WLSMV.

The standard errors for the estimated thresholds of the u* underlying these categorical variables are relatively large (ranging from about .15 to .25 in most cases), although most of the threshold estimates are significant.

Is the magnitude of SE's for these thresholds important to attend to?
 Bengt O. Muthen posted on Tuesday, September 20, 2011 - 6:47 pm
No, they typically correspond to probabilities that your are not interested in testing against.
 QianLi Xue posted on Sunday, November 27, 2011 - 7:16 pm
1. A CFA with categorical indicators was given at the site:
http://www.ats.ucla.edu/stat/mplus/seminars/IntroMplus_CFA/default.htm

And there is this statement: "A threshold is the expected value of the latent variable or factor at which an individual transitions from a value of 0 to a value of 1.00 on the categorical outcome variable when the continuous underlying latent variable's score is zero."

Is this right? Should the expected value be for the continuous underlying latent variable of the categorical indicator, not the factor? Also by "continuous underlying latent variable's score is zero" do you mean the factor score is zero?

 Linda K. Muthen posted on Monday, November 28, 2011 - 11:29 am
I would say:

A threshold is the expected value of the latent response variable at which an individual transitions from a value of 0 to a value of 1 on the categorical outcome variable.
 Melinda Gonzales-Backen posted on Tuesday, February 03, 2015 - 9:27 am
I'm running a mediation model with manifest variables. I am getting the following error: Invalid threshold value.

So far I've been unsuccessful in finding information about this error. Thanks for any feedback you might have.
 Linda K. Muthen posted on Tuesday, February 03, 2015 - 2:11 pm
 Cheng posted on Thursday, March 09, 2017 - 4:58 pm
Is there any way to simplify this command in Mplus input? For 3 items with 3 categories. intercepts are free parameter.

[y1\$1 y1\$2 y2\$1 y2\$2 y3\$1 y3\$2];
 Linda K. Muthen posted on Friday, March 10, 2017 - 10:01 am
I think [y1\$1 - y3\$2]; works. Try it out.