ARR is the difference between the control group’s event rate Control event rate (CER) and the experimental group’s event rate Experimental event rate (EER).
CER is the proportion of patients responding to control treatment.
Statistical Significance is the degree by which a value is greater or smaller than what would be expected by chance.
Statistical Significance The findings of one scientific experiment can have statistical significance but not clinical significance.
Measurements of Clinical Significance A number of measures are used to conclude clinical significance of experiments.
One of the best statistics used is the Absolute risk reduction (ARR).
RRR is the percent reduction in events in the experimental group compared to the control group event rate.
Unlike ARR, RRR amplifies small differences between the between the experimental and control interventions.
The difference is not sufficiently important to warrant clinical benefits (Burns & Grove 2007).
It is difficult to judge how much change would constitute clinical significance.