Study Designs – Cohort Studies

A public health researcher in Mumbai wants to study the long-term health outcomes of workers employed in textile mills. She enrolls 2,000 workers currently exposed to cotton dust and 2,000 workers from non-textile industries with no occupational exposure. Both groups are free of respiratory disease at baseline. She follows both cohorts for 5 years, recording the incidence of chronic obstructive pulmonary disease (COPD). What is the primary advantage of this cohort study design over a case-control study for investigating this occupational exposure-disease relationship?

A researcher wants to investigate the association between occupational exposure to asbestos and the development of lung cancer in factory workers. A group of 500 workers exposed to asbestos and 500 unexposed workers are followed for 10 years and monitored for the development of lung cancer. Which of the following best describes the study design and what measure of association would be most appropriate to calculate?