Eur J Phys Rehabil Med 2024 Feb 28;60(1):145–153

Table V. —Example of E-value calculation and interpretation in quantitative bias analysis. [31, 32]

Example of E-value calculation	Description
Observed treatment-outcome association from primary analysis (after adjusting for measured confounders)	Risk ratio (RR) = 3.8
E-value calculation using formula	E-value = RR + √[RR×(RR‒1)] = 3.8+√[3.8×(3.8‒1] = 7.1
Interpretation	• An unmeasured confounder would need to be associated with both the treatment and outcome by a risk ratio of 7.1-fold each (above and beyond measured confounders) to fully explain away the observed risk ratio of RR=3.8 • An unmeasured confounder weakly associated with treatment and outcome (i.e., less than a risk ratio of 7.1-fold each) would not be enough to fully explain away the observed risk ratio of RR=3.8 • Therefore, considerably strong confounding associations (with treatment and outcome) would be needed to fully explain away the observed treatment-outcome association of RR=3.8