For Exercises 7–10, assume that the samples were drawn independently and confirm that the other requirements for ANOVA are met by doing the following:
- Use technology to construct a probability plot for each group. Check for normality.
- Check for equal variances.
Question 12.9
9.
| A | B | C | D |
|---|---|---|---|
| 30 | 35 | 45 | 5 |
| 0 | 75 | 20 | 30 |
| 25 | 55 | 10 | 0 |
| 0 | 45 | 25 | 35 |
12.1.9
(a)
All four graphs show acceptable normality.
(b)
The smallest standard deviation is 14.72 which is the standard deviation for group C. Twice 14.72 is 29.44. All other standard deviations are less than 29.44 so the equal variance requirement is satisfied.