Identify the study design best described by the scenarios or research questions presented below. Provide a two-sentence rationale for your answer. Choose from:
• Ecologic
• Cross-sectional
• Case-control
• Retrospective (Historical) Cohort
• Prospective Cohort
• Clinical Trial
• Group or Cluster Trial
Only choose one study design for each question.
#1. To test the efficacy of a health education program in reducing the risk of food-borne and water-borne diseases, two Peruvian villages were given an intensive health education program. At the end of two years, the incidence rates of important water-borne and food-borne diseases in these villages were compared with those in two similar control villages (that did not receive an education program).
Ans: Retrospective (Historical) Cohort. At the evaluation period, the historical data (test the education program) is used at the end of the two years to determine the exposed and nonexposed group among the educated and non-educated group.
#2. You are interested in finding out whether middle-aged men who have premature heartbeats are at a greater risk of developing myocardial infarction (heart attack) than men whose heartbeats are regular. Electrocardiogram (ECG) examinations are performed on all male office employees 35 years of age or older who work for oil companies in Houston. The ECG tracings are classified as irregular or regular. Five years later, myocardial infarction rates are compared between those with and those without baseline ECG irregularities
Ans: Cross-Sectional Study. The disease and exposure are studied simultaniouly, the ECG is permformed to determined irregular and regular heart beat (prevalent cases) and compared myocardial infarction rate to with the prevalent cases of irregular and regular heart beat for individuals.
#3. To test the efficacy of vitamin C in preventing colds, army recruits are randomly assigned to one of two groups: one in which 500mg of vitamin C is administered daily and one in which 500mg of placebo is administered daily. Both groups are followed to determine the occurrence and severity of subsequent colds.
Ans: Clinical Trial. This study is based on treatment and prevention approach, more like in the community settings.
#4. The physical examination records of the incoming freshman class of 1935 at the University of Minnesota are examined in 1980 to see whether their recorded height and weight at the time of admission to the university are related to their chance of developing coronary heart disease by 1981.
Ans: Prospective Cohort. The freshman class is followed-up to observe the developing the disease.
#5. All the students at James L. Dennis High School took a survey during their homeroom class last Friday. The survey included items asking about demographics, the frequency of their back pack use during the prior 30 days, and back pain experienced during the prior 30 days.
Ans: Ecologic Study. There is no direct contact or follow-up with the students, the conclusion is drawn from the survey itself.
Please check if I am on the right track. Thanks.
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