Standardised Incidence Ratio/Standardised Mortality Ratio, SIR/SMR

The ratio between the probability of falling ill in a cohort and in a comparison group (mostly the total population).

• With an SIR/SMR of 1 there is no difference between the two groups.
• With SIR/SMR less than 1 the risk in the cohort is smaller, with SIR/SMR higher than 1 larger than in the comparison population.

By means of a significance test it can be checked how statistically significant this difference is.