Which terms describe rates used in epidemiology?

• A. Crude, specific, and adjusted.
• B. Absolute, relative, and net.
• C. Primary, secondary, and tertiary.
• D. Median, mean, and mode.

Answer: (A)

In epidemiology, rates are described in ways that let us compare populations fairly by accounting for differences in population structure. Crude rates are the overall counts per population without adjusting for any subgroup characteristics. Specific rates break the data into particular subgroups, such as by age or sex, to reveal patterns that a single overall rate might hide. Adjusted (or standardized) rates modify the crude figures to remove the influence of factors like age distribution, allowing meaningful comparisons between populations that differ in structure.

For example, comparing death rates between countries with different age profiles is more accurate when using an age-adjusted rate than a crude rate. Other terms don’t describe these rate types: absolute, relative, and net aren’t the standard categories for rate descriptions in epidemiology; primary, secondary, and tertiary refer to levels of prevention; and median, mean, and mode are measures of central tendency, not rate classifications.