A study sought to determine if the ancient Chinese art of acupuncture could help infertile women become pregnant. One hundred sixty healthy women undergoing treatment with artificial insemination were recruited for the study. Half of the subjects were randomly assigned to receive acupuncture treatment 25 minute s before embryo transfer and again 25 minutes after the transfer. The remaining 80 subjects were instructed to lie still for 25 minutes after the embryo transfer. Results: In the acupuncture group, 34 women became pregnant. In the control group, 21 women became pregnant. (a) Explain how the three principles of experimental design were addressed in this study. (b) The difference in the percent of women who became pregnant in the two groups is statistically significant. Explain to someone who knows little statistics what this means. (c) Why can't we conclude that acupuncture caused the difference in pregnancy rates?
