Epidemiology & Public Health

Intermediate

Relative Risk

How many times more likely the exposed group is to develop the disease compared to the unexposed group.

Formula

RR = \frac{\text{Risk in Exposed}}{\text{Risk in Unexposed}}

Variables

RRRelative risk

\text{Risk in Exposed}Incidence in the exposed group

\text{Risk in Unexposed}Incidence in the control group

Example

30 % incidence in exposed vs 10 % in unexposed → RR = 3

Did You Know?

RR = 1 means no extra risk from the exposure; RR > 1 suggests a harmful factor; RR < 1 suggests a protective one.

epidemiology relative risk cohort study

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More in Epidemiology & Public Health

Incidence Rate

Rate at which new cases of a disease appear in a population over a given period.

Prevalence

Proportion of a population that has a particular condition at a point in time.

Basic Reproduction Number

Average number of secondary infections produced by one infected individual in a fully susceptible population.

Herd-Immunity Threshold

Minimum fraction of the population that must be immune to prevent sustained spread.

Effective Reproduction Number

Actual average infections per case when part of the population is already immune.

SIR Model — Susceptible

Rate of change of the susceptible population in the SIR compartmental model.