Question

3. A telephone survey of university students was conducted to estimate the prevalence of respiratory disease in the student population. What type of study is this? (1 mark) a) Case-control b) Cohort c) Cross-sectional d) Longitudinal e) Cluster-randomised trial 3b. Could this study be affected by selection bias? If so, how? Answer in complete sentences. (1 mark) 3c. How would such bias affect the prevalence estimate? Answer in complete sentences. (1 mark)

Answer 1

(3a)

Question:

What type of study is this?

Correct option:

(e) Cluster-randomised trial

Explanation:

A Cluster Randomized Trial )CRT) is a trial in which individuals are ranomized in groups - the group as a whole is randomized and not the individual. In this experimentation, telephone survey of university students is conducted.

(3b)

Question:

Could this study be affected by selection bias? If so, how? Answer in complete sentences

This study could be affected by selection bias because since the survey is through telephone and there is no incentive orcompulsion to answer the survey question on the prevalence of respiratory disease in the student population, only those students who are much affected by respiratory disease will respond to the survey. Majority of the students who do not have anyespiratory disease will just ignore the telephone survey.

(3c)

Such bis would affect the prevalence estimate to a value higher than the actual prevalence of respiratory disease because the sample will consist ofmostly those students who are much affected by respiratory disease. Majority of the students who do not have anyespiratory disease will just ignore the telephone survey.