The measure reads as a proportion only when the two pieces point the
same way. With opposite signs the denominator is a difference of
magnitudes and the ratio can exceed one or go negative – information,
not an error, so it is returned with a flag rather than clamped.
Arguments
- NIE
Natural indirect effect.
- NDE
Natural direct effect.
Value
List with estimate, te, same_sign.
Details
Formula: PM = NIE / (NIE + NDE).
References
VanderWeele, T. J. (2013). Epidemiology 24:175-176;
VanderWeele (2015), Explanation in Causal Inference, section 2.7.
Examples
PropMd(NIE = 5L, NDE = 5L)
#> $estimate
#> [1] 0.5
#>
#> $te
#> [1] 10
#>
#> $same_sign
#> [1] 1
#>
#> $method
#> [1] "Proportion mediated, NIE / TE"
#>
#> attr(,"class")
#> [1] "morie_rich_result" "list"
