

Mover Stayer Single Variable Model 

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Chris Weber posted on Thursday, December 05, 2013  9:44 am



I am estimating a simple mover stayer model with a three category variable measured at five time points. Since the latent classes for each of the five waves is measured with a single variable, I constrain the item thresholds. Yet, I get the following error for each class: *** ERROR in MODEL command One or more pairs of ordered thresholds are not increasing in Class 1. Check your starting values. Problem with the following pairs: PID_1$1 (15.000) and PID_1$2 (15.000) PID_2$1 (15.000) and PID_2$2 (15.000) ..... Any tips on how to do this? Clases are specified as follows: classes= c(2) c1(3) c2(3) c3(3) c4(3) c5(3); !c is mover stayer At the end of the file, I constrain the thresholds for each of the three classes within the five latent variables (t1t5). This generates the error. For instance: model c1: %c1#1% [pid_1$1@15]; [pid_1$2@15]; %c1#2% [pid_1$1@15]; [pid_1$2@15]; %c1#3% !baseline [pid_1$1@15]; [pid_1$2@15]; model c2: %c2#1% [pid_2$1@15]; [pid_2$2@15]; ....and so forth. Thanks. 


You have to order the threshold values from low to high. So [pid_1$1@15]; [pid_1$2@20]; corresponds to falling in the lowest of the 3 categories, [pid_1$1@15]; [pid_1$2@15]; corresponds to falling in the middle category, and [pid_1$1@20]; [pid_1$2@15]; corresponds to falling in the highest of the 3 categories. Note that the threshold values are always increasing. 


Dear Drs. Muthen, I am trying to estimate a LTA moverstayer model as per example 8.15. I had the same issue as above when attempting to constrain for equality (ordered thresholds not increasing), and was able to run the model by changing: %c1$1% [c1_est$1] (1) to: %c1$1% [c1_est$1@15] (1) Is this the correct way to specify the order of the threshold values? c1_est contains 5 classes: is it acceptable to specify only the first threshold, or do I need to specify the threshold for each class? Thank you, Justin 


You are using @, so fixing the threshold, which means that the equality constraint does not take effect. With 5 categories you could instead say for example [c1_est$1*.2] (1); [c1_est$2*.1] (2); [c1_est$3*.1] (3); [c1_est$4*.2] (4); 

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