Yes, if you can avoid plucking values from the display tree that's usually a good strategy. If you want to get the values into variables, you can do something like this ('levels' will be a list, 'vals' a matrix):
NamesDefaultToHere(1);
dt = Open("$SAMPLE_DATA/Big Class.jmp");
tab =
dt << Tabulate(
Show Control Panel( 0 ),
Add Table(
Column Table( Grouping Columns( :age ) ),
Row Table( Analysis Columns( :height ), Statistics( Mean ) )
)
);
dt2 = tab << makeIntoDataTable;
dt2 << setName("Tabulation from "||(dt << getName));
cols = dt2 << getColumnNames(:String);
RemoveFrom(cols, 1, 2);
dt3 = dt2 <<
Transpose(
columns(Eval(cols)),
Transpose selected rows only( 1 ),
Label( :Statistics ),
Output Table( (dt2 << getName) )
);
levels = Column(dt3, "Label") << getValues;
vals = Column(dt3, "Mean") << getValues;
Close(dt2, NoSave);
Close(dt3, NoSave);