Question

Identify which of the following five types of study designs most appropriately characterizes each of the situations described below. You may use a particular study design more than once, but give only one answer per item.

                             A.           Cross-sectional study                                  D.               Clinical trial

                             B.           Case-control study                                       E.              Community trial

                             C.           Prospective cohort study

                            

1) Two groups are recruited into the study – one of the groups is a random sample of all skin cancer cases in the New York metropolitan area. The other group is selected from residents of New York who are matched to the first group on age, sex, and place of residence. A survey asks the participants about their sunscreen use in the past 5 years.

2) Eight counties in California are trying to determine if a smoking prevention education campaign works to lower smoking rates among adolescents. Four of the counties receive the intervention, while the other four do not. After a year, smoking rates are compared.

3) A group of battery manufacturing factory workers is recruited to participate in a 10 year study to determine the effects of a particular chemical on health. Another group from the same company, but who only work in the offices, is recruited alongside them. Every 2 years, a follow-up study is done which assesses the health status of all workers.

4) A study determining the efficacy of a blood pressure medication recruits 300 people and randomly assigns them into one of three groups – one that receives no medication, one that receives a placebo, and one that receives the medication being studied. After 6 months, participants are assessed for symptoms of high blood pressure.

5) A large, nationally-representative survey that asks participants about their alcohol, tobacco and drug use, and demographic information. This is administered to different samples every 3 years in order to characterize the trends of drug use in the United States.

Answer 1

1)Cross sectional study

it is a observational study

it just compares two groups at one point of time and analysis it

2) prospective cohort study

after an intervention we are taking the survey

both samples disease has not occured

3) Prospective cohort study

-outcome has not occured

- it starts from present and continue to future

- development of a disease in those who are exposed and development of the same disease in non exposed in a particular time period

4) clinical trial

--evaluation of a therapeutic agent

5) community trial