convert_measures {EValue}

Convert an effect measure

Description

These helper functions are mostly used internally to convert effect measures for the calculation of E-values. The approximate conversion of odds and hazard ratios to risk ratios depends on whether the rare outcome assumption is made.

Usage

toRR(est, rare, delta = 1, ...)

toMD(est, delta = 1, ...)

Arguments

est

The effect estimate; constructed with one of RR(), OR(), HR(), MD(), OLS().

rare

When converting a OR() or HR() estimate, a logical indicating whether the outcome is sufficiently rare to approximate a risk ratio.

delta

When converting an OLS() estimate, the contrast of interest in the exposure. Defaults to 1 (a 1-unit contrast in the exposure).

...

Arguments passed to other methods.

Details

Uses the conversions listed in Table 2 of VanderWeele TJ, Ding P. Sensitivity Analysis in Observational Research: Introducing the E-Value. Annals of Internal Medicine. 2017;167(4):268–75.

See references.

Regarding the continuous outcome, the function uses the effect-size conversions in Chinn (2000) and VanderWeele (2017) to approximately convert the mean difference between these exposure "groups" to the odds ratio that would arise from dichotomizing the continuous outcome.

Value

An object of class "estimate" and the desired effect measure. Also includes as an attribute its conversion history.

References

Chinn, S (2000). A simple method for converting an odds ratio to effect size for use in meta-analysis. Statistics in Medicine, 19(22), 3127-3131.

VanderWeele, TJ (2017). On a square-root transformation of the odds ratio for a common outcome. Epidemiology, 28(6), e58.

VanderWeele TJ (2020). Optimal approximate conversions of odds ratios and hazard ratios to risk ratios. Biometrics.

Examples

# Both odds ratios are 3, but will be treated differently
# depending on whether rare outcome assumption is reasonable
OR(3, rare = FALSE)
OR(3, rare = TRUE)
toRR(OR(3, rare = FALSE))
toRR(OR(3, rare = TRUE))
attributes(toRR(toMD(OLS(3, sd = 1.2), delta = 1)))