When is relative risk statistical significance

By convention we typically regard the unexposed or least exposed group as the comparison group, and the proportion of successes or the risk for the unexposed comparison group is the denominator for the ratio.

The relative risk is a ratio and does not follow a normal distribution, regardless of the sample sizes in the comparison groups. However, the natural log Ln of the sample RR, is approximately normally distributed and is used to produce the confidence interval for the relative risk. Therefore, computing the confidence interval for a risk ratio is a two step procedure.

First, a confidence interval is generated for Ln RR , and then the antilog of the upper and lower limits of the confidence interval for Ln RR are computed to give the upper and lower limits of the confidence interval for the RR. Note that the When computing a risk difference, however, the null value indicating no differernce between the groups is 0. When we were calculating risk ratios and odds ratios, the null value would be 1, i. When computing a risk difference, however, the null value indicating no differernce between the groups is 0.

The outcome of interest was all-cause mortality. Links to PubMed are also available for Selected References. These references are in PubMed. This may not be the complete list of references from this article. National Center for Biotechnology Information , U.

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RRR is usually constant across a range of absolute risks. If a person's AR of stroke, estimated from his age and other risk factors, is 0. In a person with an AR of stroke of only 0. Note To express decimals as percentages, multiply by