The FAMILY Procedure

The TRAIT statement identifies the trait variable and is required when the OUTQ= option is omitted. This variable must be binary, but it can be either character or numeric. By default, the second value of the TRAIT variable that appears in the input data set is considered to be "affected" for the tests. To specify a different value for "affected," add the /AFFECTED=value option to the TRAIT statement. For a variable with a numeric format, the number that corresponds to "affected" should be specified (AFFECTED=1); if the variable has a character format, the level that corresponds to "affected" should be specified in quotes (AFFECTED="a").