One option is to use matrix calculations (as a reminder JMP is Not a Spreadsheet ) and Data table subscripting
Names Default To Here(1);
dt = New Table("Untitled 2",
Add Rows(3),
Compress File When Saved(1),
New Column("Column 1", Numeric, "Continuous", Format("Best", 12), Set Values([1, 2, 2])),
New Column("Column 2", Numeric, "Continuous", Format("Best", 12), Set Values([3, 4, 3])),
New Column("Column 3", Numeric, "Continuous", Format("Best", 12), Set Values([7, 8, 9]))
);
myvals = dt[1::2, 1::2];
myavg = Mean(myvals);
mymax = Max(myvals);
https://www.jmp.com/support/help/en/17.2/#page/jmp/additional-ways-to-access-data-values.shtml#
-Jarmo