Here is one way to get the Y column name
Names Default To Here( 1 );
dt = Open( "$SAMPLE_DATA/Variability Data/2 Factors Crossed.jmp" );
obj = dt << variability chart( Y( :Measurement ), X( :Operator, :part# ) );
// Parse the returned script to find the specified Y column
theYColumn = Word(
1,
Substr( Char( obj << get script ), Contains( Char( obj << get script ), "Y(:" ) + 3 ),
"),"
);
Jim