I'm trying to specify a SEM in which I only need observations whose zygosity has been labeled 1 or 2 in the .sav and later .dat file. The original .dat file contains 3931 observations; minus those observations that should not be included because they are labeled with 0 or -99 in the zygosity item, there should be 2812 observations left. However, mPlus gives me a number of 3422 observations. Is there any logic error in my USEOBSERVATIONS section or did I miss anything else?
USEOBSERVATIONS ARE (MAOA_ZYG EQ 1 OR MAOA_ZYG EQ 2);