A prospective double-blind clinical trial was conducted in 11 young, health, normally menstruating female subjects to detect any differences in energy intake in the pre and post phases of the menstrual cycle. The data is shown in Table 8.14.

(a) Write out a suitable null and alternative hypothesis for this problem and data.

(b) Do these data suggest that the mean daily dietary intake over the 10 pre and 10 post-menstrual days is different? Stating any assumptions you make, perform an appropriate hypothesis test to compare mean daily dietary intake (kJ/day) between the pre and post-menstrual phases in this sample of 11 women. Comment on the results of this hypothesis test.

(c) Calculate a 95% CI for the difference in mean daily dietary intake (kJ/day) between the pre and post-menstrual phases in this sample of 11 women. Discuss whether the confi dence interval suggests that women might have a lower dietary intake in the post-menstrual phase than women in the pre-menstrual phase.