A Swedish study used 1360 patients who had suffered a stroke. The study randomly assigned each subject to an aspirin treatment or a placebo treatment. 4 The table shows MINITAB output, where X is the number of deaths due to heart attack during a follow-up period of about 3 years. Sample 1 received the placebo and sample 2 received aspirin.
a. Explain how to obtain the values labeled €œSample p.€
b. Explain how to interpret the value given for €œestimate for difference.€
c. Explain how to interpret the confidence interval, indicating the relevance of 0 falling in the interval.
d. If we instead let sample 1 refer to the aspirin treatment and sample 2 the placebo treatment, explain how the estimate of the difference and the 95% confidence interval would change. Explain how then to interpret the confidence interval. (The output below would change for the analysis of this difference.)

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Sample x Sanple p 28 18 684 .040936 676 0.026627 DiFferencepi P 2) Estimate Eor difference: 0.0143085 95% CI for difference [-0.00486898 , 0:0334859) Test Eor difference - 0 (vs not 0): Z=1.46 p-Va