A study was undertaken to compare the respiratory responses of hypnotized and non-hypnotized subjects to certain instructions. The 16 male volunteers were allocated at random to an experimental group to be hypnotized or to a control group. Baseline measurements were taken at the start of the experiment. In analyzing the data, the researchers noticed that the baseline breathing patterns of the two groups were different; this was surprising, since all the subjects had been treated the same up to that time. One explanation proposed for this unexpected difference was that the experimental group were more excited in anticipation of the experience of being hypnotized. The accompanying table presents a summary of the baseline measurements of total ventilation (liters of air per minute per square meter of body area). Parallel dotplots of the data are given in the following graph.

(a) Use a t test to test the hypothesis of no difference against a non-directional alternative. Let α = 0.05.
(b) Use a t test to test the hypothesis of no difference against the alternative that the experimental conditions produce a larger mean than the control conditions. Let α = 0.05.
(c) Which of the two tests, that of part (a) or part (b), is more appropriate? Explain.

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Experimental Control 5.32 5.60 5.74 6.06 6.32 6.34 6.79 7.18 4.50 4.78 4.79 4.86 5.41 5.70 6.08 6.21 6.169 5.291 0.621 0.652 6.5 5.0 Experimental Control