The article “Acupuncture for Bad Backs: Even Sham Therapy Works” (Time, May 12, 2009) summarized a study conducted by researchers at the Group Health Center for Health Studies in Seattle. In this study, 638 adults with back pain were randomly assigned to one of four groups. People in group 1 received the usual care for back pain. People in group 2 received acupuncture at a set of points tailored specifically for each individual.

People in group 3 received acupuncture at a standard set of points typically used in the treatment of back pain.

Those in group 4 received fake acupuncture—they were poked with a toothpick at the same set of points used for the people in group 3! Two notable conclusions from the study were: (1) patients receiving real or fake acupuncture experienced a greater reduction in pain than those receiving usual care; and (2) there was no significant difference in pain reduction for those who received acupuncture (at individualized or the standard set of points) and those who received fake acupuncture toothpick pokes.

a. Is this study an observational study or an experiment? Explain.

b. Is it reasonable to conclude that receiving either real or fake acupuncture was the cause of the observed reduction in pain in those groups compared to the usual care group? What aspect of this study supports your answer?