Dr. Franklin investigated the relationship between stress and physical lness. She persuaded a high school principal to require all female athletes in the school to participate in her study. She explained the purpose of her research to the athletes and asked them to use a standard form to rate the severity of their stress over the last six months. More than 250 athletes completed the form. Then Dr. Franklin analyzed the forms returned by the first 100 athletes, She requested the attendance records from the nurse's office for each of those athletes to verify the number of days absent due to illness during the same six-month period. In the debriefing summary that Dr. Franklin sent to the 100 athletes after she completed the study, she stated that athletes who reported more stress also experienced more frequent illness. Dr. Franklin condluded that stress causes physical illiness. Describe the operational definitions of the TWO key variables that Dr. Franklin used in the study. • Based on the information provided, describe ONE appropriate and ONE inappropriate ethical feature of the study. Describe TWO aspects of experimental research design that weaken the validity of Dr. Franklin's conclusion that stress causes physical illness.