In a pilot study examining the effectiveness of three com¬mercials (A, B, and C), 10 consumers were assigned to view each commercial and rate it on a 9-point Likert scale. The data obtained from the 30 respondents are shown in the table.
Commercial
A B C
4 7 8
5 4 7
3 6 7
4 5 6
3 4 8
4 6 7
4 5 8
3 5 8
5 4 5
5 4 6
a. Calculate the category means and the grand mean. Show Calculations.
b. Calculate SSy, SSx, and SSerror. Show Calculations.
c. Calculate eta2. Show Calculations.
d. Calculate the value of F. Show Calculations.
e. Are the three commercials equally effective?