IBM® SPSS® Amos™ 28

The category boundaries and the model parameters should in principle be estimated simultaneously, but that is not computationally practical. Instead, a two-stage procedure is used. The category boundaries are chosen in the first stage. Then in the second stage, posterior distribution of the parameters and possibly also predictive posterior distributions are estimated.

In the first stage, where category boundaries are chosen, you can specify values for the category boundaries yourself. Alternatively, you can let Amos estimate the boundaries. When Amos estimates the boundaries, its approach depends on the number of categories.