On page 11 in Section 1.1, we describe studies to investigate whether there is evidence of pheromones (subconscious chemical signals) in female tears that affect sexual arousal in men. In one of the studies, 50 men had a pad attached to the upper lip that contained either female tears or a salt solution dripped down the same female’s face. Each subject participated twice, on consecutive days, once with tears and once with saline, randomized for order, and doubleblind. Testosterone levels were measured before sniffing and after sniffing on both days. While normal testosterone levels vary significantly between different men, average levels for the group were the same before sniffing on both days and after sniffing the salt solution (about 155 pg/mL) but were reduced after sniffing the tears (about 133 pg/mL). The mean difference in testosterone levels after sniffing the tears was 21.7 with standard deviation 46.5.

(a) Why did the investigators choose a matchedpairs design for this experiment?

(b) Test to see if testosterone levels are significantly reduced after sniffing tears?

(c) Can we conclude that sniffing female tears reduces testosterone levels (which is a significant indicator of sexual arousal in men)?