One-Way ANOVA: Promotion Effects on Sales

A study compared the effects of four 1-month point-of-purchase promotions on sales. The unit sales for five stores using all four promotions in different months follow.

TABLE STORE
I II III IV V
SALES PROMOTION TYPES Free Sample 78 87 81 89 85
One-pack gift 94 91 87 90 88
Cents off 73 78 69 83 76
Refund by mail 79 83 78 69 81

Use one-way ANOVA to determine whether different promotions produce different effects on sales. (α = 0.05).