In a study, an RR of 1.0 for a negative outcome indicates which of the following?

• A. Exposed have higher risk.
• B. Exposed have lower risk.
• C. There is no association between exposure and the outcome.
• D. The result is inconclusive due to measurement error.

Answer: (C)

Relative risk compares how often the outcome occurs in the exposed group versus the unexposed group. An RR of 1.0 means the risks are the same in both groups, so the exposure does not change the probability of experiencing the negative outcome. In other words, there is no association between the exposure and the outcome based on that point estimate. Keep in mind that whether this is statistically significant depends on the confidence interval: if it includes 1, the result isn’t significant; if it excludes 1, the lack of association is statistically supported. A higher RR would indicate increased risk with exposure, while a lower RR would indicate decreased risk.