A local health agency is experimenting with two appeal letters, A & B, with which to raise funds.  It sends out 400 of the A appeal and 400 of the B appeal (each subsample is divided equally among working-class and middle-class neighborhoods).  The agency secures the results shown in the following table.

1. Which appeal is the best
2. Which class responded better to which letter?
3. Is appeal or social class a more powerful independent variable?

Appeal A                               Appeal B

Middle   Working                Middle      Working

Class       Class                       Class         Class

(%)           (%)                          (%)            (%)

Contribution                  20            40                            15             30

No Contribution            80            60                            85             70

100          100                         100           100