The Whitehall study is a ground-breaking longitudinal (prospective cohort) study that clearly demonstrated the association between social determinants of health (the social gradient) and morbidity and mortality (cardiovascular disease) in a population of British civil servants (Breeze et al., 2001; Chandola et al., 2008; Marmot et al., 1978). Read these papers and answer the following questions.

1. What is the sampling frame for each phase of the Whitehall study (Whitehall I and II)?

2. How was disease risk assessed (both in data collection and analysis) in each of the three studies and why?