Dear Dr Muthen I am trying to define transformed parameters in the MODEL CONSTRAINT section for the purpose of an IRT analysis I am doing. I would like to drfine a new parameter in a different way depending on whether the sign of another parameter is (+) or (-). It seems the system does not recognise functions like SIGN or SIGNUM, nor does it accept IF type of conditioning in the MODEL CONSTRAINT section. Any idea how to go around this problem is much appreciated. Thanks, Spiro
Conditional statements cannot be used in MODEL CONSTRAINT. Linear and non-linear constraints can be defined using the equal sign (=), the greater than sign (>), the less than sign (<), and all arithmetic operators and functions that are available in the DEFINE command with the exception of the absolute value function.