Caffeine is the world's most widely used stimulant, withapproximately 80% consumed in the form of coffee. Participants in astudy investigating the relationship between coffee consumption andexercise were asked to report the number of hours they spent perweek on moderate (e.g., brisk walking) and vigorous (e.g.,strenuous sports and jogging) exercise. Based on these data theresearchers estimated the total hours of metabolic equivalent tasks(MET) per week, a value always greater than 0. The table belowgives summary statistics of MET for women in this study based onthe amount of coffee consumed.
Caffeinated coffee consumption
| ≤ 1 cup/week (1) | 2-6 cups/week (2) | 1 cup/day (3) | 2-3 cups/day (4) | ≥ 4 cups/day (5) | Total |
---|
Mean | 18.7 | 19.6 | 19.3 | 19.9 | 17.5 | |
SD | 21.1 | 25.5 | 22.5 | 22 | 22 | |
n | 12215 | 6617 | 17234 | 12290 | 2383 | 50739 |
(a) Write the hypotheses for evaluating if the average physicalactivity level varies among the different levels of coffeeconsumption.
- A: Ho: μ1 = μ2 = μ3 =μ4 = μ5
Ha: μ1 ≠μ2 ≠μ3 ≠μ4 ≠μ5 - B: Ho: μ1 = μ2 = μ3 =μ4 = μ5
Ha: At least one pair of means is the same - C: Ho: μ1 = μ2 = μ3 =μ4 = μ5
Ha: At least one of the means is different
(b) Assume that all of the conditions required for thisinference are satisfied.
(c) Below is part of the output associated with this test. Fill inthe empty cells.
| Df | Sum Sq | Mean Sq | F value | Pr(>F) |
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coffee | | | | | 0.0003 |
residuals | | 25564819 | | | |
total | | 25575327 |
(d) What is the p-value associated with the ANOVA test?
p =
(e) What is the conclusion of the test?
- A: Since p < α we reject the idea that all of the means arethe same and accept that all of the means are different
- B: Since p < α we reject the idea that all of the means arethe same and accept that at least one of the means isdifferent
- C: Since p < α we reject the idea that all of the means aredifferent and accept that all of the means are the same
- D: Since p<α we reject the idea that at least one of themeans is different and accept that all of the means are thesame