1. Prospective Cohort Study (Click or press Enter to follow animation)
Begin enquiry here & work forwards
Outcomes
Disease (a)
Some have the factor (c)
Sample people without the disease
No Disease
Population
Disease (b)
Some do not (d)
No Disease
(lapse of time)
Statistic = Relative Risk [RR] = (a/c) divided by (b/d) This shows the ratio of incidence in exposed compared to non-exposed. RR > 1 implies a hazard; RR < 1 implies a protective factor 95% CI are usually presented: e.g., RR = 1.9 (95% CI 1.5, 2.3)
Note: as you begin with people who do not have the disease, you can calculate incidence but not prevalence. (Prevalence would be underestimated as you omitted existing cases)