An experiment tested the effects of package design and display on the likelihood of purchase of Product 19 cereal Package design and shelf display were varied at two levels each, resulting in a 2 X 2 design. Purchase likelihood was measured on a 7-point scale. The results are partially described in the following table.
Source of Sum of Mean Omega2
Variation Squares df Square F
Package design 68.76 1
Shelf display 320.19 1
Two way interaction 55.05 1
Residual error 176.00 40
a) Complete the table by calculating the mean square, F, significance of F, and Omega2 values.
b) How should the main effects be interpreted?