You use the CUTPOINT option of the MONTECARLO command. See Example 11.1 in the Mplus User's Guide. The value given is a z-score. So you use a z-score table to select the value that corresponds to a 75/25 split.
June Zhou posted on Thursday, February 07, 2013 - 3:17 pm
I have a similar question about generating a binary independent variable in a Monte Carlo simulation. I'd like to generate "Gender" variable that with population mean of 0.5 and variance of 0.25. What code should I use? Thank you in advance.