An epidemiology report measures the proportion of a population that has a disease at a single point in time. Which measure is this?

Prevalence is the proportion of existing cases at a specific point in time; incidence counts only new cases over a period.Other options: Incidence is new cases over time; relative risk compares risks between groups; attack rate applies to outbreaks over a defined period.Key exam takeaway: Prevalence = all existing cases at one time; incidence = new cases over time.