Name: Date: Period: 63. Do diets work? Dr. Linda Stem and her colleagues pg 243 recruited 132 obese adults at the Philadelphia Veterans Affairs Medical Center in Pennsylvania. Half the participants were randomly assigned to a low- carbohydrate diet and the other half to a low-fat diet. Researchers measured each participant's change in weight and cholesterol level after six months and again after one year. Explain how each of the four principles of experimental design was used in this study. 65. Headache relief Doctors identify "chronic tension- pg 245 type headaches" as headaches that occur almost daily for at least six months. Can antidepressant med- ications or stress management training reduce the number and severity of these headaches? Are both to- gether more effective than either alone? Researchers want to compare four treatments: antidepressant alone, placebo alone, antidepressant plus stress management, and placebo plus stress management. Describe a completely randomized design involving 36 headache sufferers who are willing to participate in this experiment. Write a few sentences describing how you would implement your design