Indirect adjustment does not require knowledge of actual age-specific rates among each age group. Which statement best describes indirect adjustment?

• A. It compares a population's rates to a standard population's rates.
• B. It does not require knowledge of actual age-specific rates among each age group.
• C. It uses a completely outside standard population to compute adjusted rates.
• D. It estimates expected deaths using observed rates in the study population.

Answer: (B)

Indirect adjustment focuses on removing the influence of different age structures by using external, standard age-specific rates and applying them to the study population’s age distribution. You take those standard rates and apply them to how many people you actually have in each age group in your study population to estimate how many deaths would be expected if the study population experienced those rates. Then you compare the observed deaths to this expected number, often as a standardized mortality ratio. The crucial point is that you don’t need the study population’s own age-specific rates; you rely on the standard rates instead. That makes the statement true. The other descriptions are less precise because they either don’t emphasize applying standard rates to the study population’s age structure or imply using the study’s own age-specific rates, which indirect adjustment does not require.