Swedish researchers concluded that viewing and discussing art soothes the soul and helps relieve medical conditions such as high blood pressure and constipation (AFP International News Agency, October 14, 2005). This conclusion was based on a study in which 20 elderly women gathered once a week to discuss different works of art. The study also included a control group of 20 elderly women who met once a week to discuss their hobbies and interests. At the end of four months, the art discussion group was found to have a more positive attitude and lower blood pressure and used fewer laxatives than the control group. a. Why is it important to determine if the researchers randomly assigned the women to one of the two groups?
b. Explain why you think that the researchers included a control group in this study.