A random sample of 50 subjects received biofeedback training to reduce blood pressure. Researchers measured the decrease in blood pressure for each of them; the average decrease was 11.4, and the SD was 1.3. A second sample of 40 control subjects had an average decrease in blood pressure during the study of 5.0, with an SD of 1.4.
(a) Construct a 95% confidence interval for the population difference average in blood pressure decrease between treatment (biofeedback) and control patients.
(b) Consider just the treatment (biofeedback) group. True or false: We can estimate that roughly 95% of all persons given biofeedback training will experience a decrease in blood pressure in the range 11.4 ± 2(1.3), that is, between 8.8 and 14.0. Explain your reasoning.