Why should you adjust rates?

• A. Presence of confounding
• B. To make calculations easier
• C. To increase observed cases
• D. To remove need for denominator

Answer: (A)

Adjusting rates is about controlling for confounding when comparing how often events occur in different groups. A confounder is a factor related to both the exposure and the outcome that can distort the apparent relationship. By adjusting—through direct or indirect standardization or through regression— you hold the confounder’s distribution constant across groups. This allows the comparison to reflect the true effect of the exposure, not differences driven by the confounder (for example, comparing mortality across populations after accounting for differing age structures with age-standardized rates). It’s not done to simplify calculations, it doesn’t create more observed cases, and the denominator is still needed for rate calculations.