Names Default to Here( 1 );
dt1 = Open( "$SAMPLE_DATA/Big Class.jmp" );
dt2 = Open( "$SAMPLE_DATA/Fitness.jmp" );
dt1 << New Column( "Outlier", Formula( :height > 65 ) );
n outliers = Col Sum( dt1:Outlier );
Here I used another data column with a formula that uses the expression to test for an outlier. This result tells me that Col Sum() might not be intended to work with any expression but specifically with a data column. (Hint, hint: COL SUM().) I don't know where the value of 4 came from when using the expression for the outlier test instead of a data column reference.