Table 8.13 shows the results of a randomised, double-blind, placebo-

controlled trial examining whether patients with chronic fatigue syndrome (CFS) improved 6 weeks after treatment with intramuscular magnesium.

The group who received the magnesium were compared to a group who received a placebo and outcome was feeling better (Cox et al, 1991).

(a) Do these data suggest that the magnesium-treated CFS patients have different outcomes to placebo treated patients after 6 weeks of treatment? Stating any assumptions you make, perform an appropriate hypothesis test to compare the difference in proportions feeling better between the Magnesium and Placebo treated groups. Comment on the results of this hypothesis test.

(b) Calculate a 95% CI for the difference in the proportion of patients feeling better between the Magnesium and Placebo groups. Does the CI estimate from this data suggest that patients in the Magnesium group have a better outcome at six weeks than patients in the Placebo group?