Biostatistics

Question:

An investigator wants to study the effects of smoking on subsequent development of lung cancer. She gathers a group of 100 smokers and 100 non-smokers and follows them for 20 years to compare rates of development of lung cancer. This investigation is an example of which type of study?

Correct Answer: B.  Cohort

This study examines whether smokers are more likely to develop lung cancer than non-smokers. It is an example of a prospective, observational, cohort study (choice B), in which a group with a risk factor (smoking) is compared to a group without the risk factor to assess whether the risk factor increases the likelihood of developing the disease.

Case-Control studies (Choice A) are observational, retrospective studies in which a group of people with a given disease (lung cancer) are compared to a group without to assess the impact of a particular risk factor.

Cross-sectional studies (choice C) collect data from a group of people at a specific point in time to assess prevalence of a particular disease and risk factors. It can be used to demonstrate associations between risk factors and diseases but not causality.

A meta-analysis (choice D) is a a study that pools together data from several separate studies to achieve greater statistical power.

A randomized double-blind control trial (choice E) is used to measure the effectiveness of an intervention compared to another intervention or placebo.