7.71 Comparison of dietary composition. Refer to Example 7.15 (page 443). That study also broke down the dietary composition of the main meal. The following table summarizes the total fats, protein, and carbohydrates in the main meal (g) for the two groups:
| Early eaters (n = 202) | Late eaters (n = 200) | ||||
|---|---|---|---|---|---|
| s | s | ||||
| Fats | 23.1 | 12.5 | 21.4 | 8.2 | |
| Protein | 27.6 | 8.6 | 25.7 | 6.8 | |
| Carbohydrates | 64.1 | 21.0 | 63.5 | 20.8 | |
(a) Is it appropriate to use the two-sample t procedures that we studied in this section to analyze these data for group differences? Give reasons for your answer.
(b) Describe appropriate null and alternative hypotheses for comparing the two groups in terms of fats consumed.
(c) Carry out the significance test using . Report the test statistic with the degrees of freedom and the P-value. Write a short summary of your conclusion.
(d) Find a 95% confidence interval for the difference between the two means. Compare the information given by the interval with the information given by the significance test.