A pain-killing drug was tested for efficacy in 50 women who were experiencing uterine cramping pain following childbirth. Twenty-five of the women were randomly allocated to receive the drug, and the remaining 25 received a placebo (inert substance). Capsules of drug or placebo were given before breakfast and again at noon. A pain relief score, based on hourly questioning throughout the day, was computed for each woman. The possible pain relief scores ranged from 0 (no relief) to 56 (complete relief for 8 hours). Summary results are shown in the table.

(a) Test for evidence of efficacy using a t test. Use a directional alternative and α = 0.05.
(b) If the alternative hypothesis were non-directional, how would the answer to part (a) change?

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Pain relief score Treatment Drug Placebo n Mean SD 25 3196 12.05 25 25.32 13.78