Improvement in quality of life was measured for a group of heart disease patients after 8 weeks in an exercise program. This experimental group was compared to a control group who were not in the exercise program.
Quality of life was measured using a 21-item questionnaire scores of 1-5 on each item. The improvement data are as follows and are plotted below:

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(a) What is the null hypothesis for a t test here?
(b) What do the dotplots suggest about H0?
(a) Here is computer output for a t test. Explain what the P-value means in the context of this study.
t = 2.505, df = 33.23, p-value = 0.00866
alternative hypothesis: true difference in means is greater than 0
(d) If α = 0.01, what is your conclusion regarding H0? State your conclusion in the context of the research.
(e) The computer output in part (c) is for the directional test. What is the P-value for the nondirectional test?
(f) If the test were nondirectional, and α = 0.01, what conclusions would we make?

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