Question

Chapter 13 Data Set 3 contains the average sales for five stores across four seasons. Which season was the best of all for sales?

Figure 13.3 Data for a Single-Factor Analysis of Variance A C Group 1 Group 2 Group 3 (5 hours) (10 Hours) (20 Hours) 1 87 87 89 3 86 85 91 76 99 96 56 85 87 78 79 89 7 98 81 90 77 82 89 66 78 96 10 75 85 96 11 67 91 93 H28456n 89 S

Answer 1

A C D E G H J K M N 1 Group 1 Group 2 87 Group 3 87 89 2 Anova: Single Factor 3 86 91 85 96 76 99 SUMMARY 4 5 56 85 87 Groups Group 1 Group 2 Group 3 Count Sum Average 766 Variance 89 6 79 78 10 76.6 143.1556 98 10 852 7 81 90 85.2 38.4 82 89 10 91.6 11.6 8 77 916 96 66 78 10 75 85 96 93 11 67 91 ANOVA F crit Source of Varie 12 SS di MS P-value Between G 1133.067 8.80 13 2 566.5333 0.00 3.35 14 Within Gro 1738.4 27 64.38519 15 Total 16 2871.467 29 17 18

Conclusion: if F > F crit, we reject the null hypothesis. This is the case, 8.80 > 3.35. Therefore, we reject the null hypothesis. The means of the three populations are not all equal. At least one of the means is different. However, the ANOVA does not tell you where the difference lies.

Group 3 looks different because average value is 91.6 and it has very less variance than other two groups