Which of the following six study design types most appropriately characterizes the studies described below (#1-6)? DESIGN TYPES a. Cross-sectional b. Case-control c. Prospective cohort d. Retrospective (historical) cohort e. Clinical trial f. Community trial STUDY DESCRIPTIONS 1.To test the efficacy of a health education program in reducing the risk of foodborne and waterborne diseases, two Peruvian villages were given an intensive health education program. At the end of the two years the incidence rates of important foodborne and waterborne diseases in these villages were compared to those in two similar control villages where no health education programs had been implemented. 2.You would like to assess the effectiveness and efficiency in delivering health services through your clinic. After selecting a 10% sample of all patient visits during the past six months, you are able to characterize the patient population utilizing your clinic in terms of age, race, sex, method of referral, diagnostic category, therapy provided, method of payment, daily patient load, and clinic work schedules. 3.You are interested in finding out whether middle-aged men who have premature heartbeats are at greater risk of developing a myocardial infarction (heart attack) than those men whose heartbeats are regular. Electrocardiogram (ECG) examinations are performed on all male employees 35 years and older who work for an oil company in your city. The ECG tracings are classified as regular or irregular by a trained cardiologist. Five years later, the heart attack rates are compared for between those with and those without baseline ECG irregularities. 5.The physical exam records of the incoming freshmen of 1935 at the University of Minnesota are examined in 1980 to see if their recorded height and weight at the time of their admission to the university are related to their risk of developing coronary heart disease by 1981.6.The entire population of a given community is examined and all who are judged to be free of bowel cancer are questioned extensively about their diets. These people are then followed for several years to see whether or not their eating habits will predict their risk of developing bowel cancer.