Principles of Public Health Exam 1

Comparing how likely an event is in one group versus another is best captured by a relative risk ratio. This measure takes the probability of the health event in the first group and divides it by the probability in the second group, giving a straightforward sense of how many times higher (or lower) the risk is in the first group. For example, if 20% of people with a factor experience the event and 5% without the factor do, the relative risk is 0.20 / 0.05 = 4, meaning the risk is four times higher in the exposed group. This directly answers the question by quantifying the comparative risk between groups. Other options are more general or describe different concepts: a simple ratio doesn’t specify which probabilities are being compared; rates or proportions describe frequency in a population but aren’t inherently a comparative risk measure between two groups; infectivity refers to how easily a disease spreads, not a general cross-group risk comparison.