COCA survival mediation estimator: NOT supported (returns NA)

COCA mediation regresses the negative control W on the outcome Y in both stages (W ~ M + X, W ~ y + X + M), placing the outcome on the right-hand side. This is structurally impossible when the outcome is a survival::Surv object. COCA mediation is therefore unsupported for survival outcomes and always returns NA.

Usage

fit_coca_mediation_surv(time, event, X, M, w, covars = NULL, ...)

Arguments

time

Numeric follow-up time vector (length n).

event

Numeric 0/1 event indicator (length n).

X

Numeric exposure vector (length n).

M

Numeric mediator vector (length n).

w

Numeric NC vector (length n).

covars

Optional data frame of covariates (n rows).

...

Ignored (signature compatibility).

Value

All-NA list with an informative "reason" attribute.

Examples

set.seed(1)
dat <- generate_toy_data(n = 200, outcome_type = "survival", seed = 1)
fit_coca_mediation_surv(dat$surv_time, dat$surv_event, dat$X, dat$M, dat$W[, 1])
#> $NDE
#> [1] NA
#> 
#> $NDE_se
#> [1] NA
#> 
#> $NDE_p
#> [1] NA
#> 
#> $NIE
#> [1] NA
#> 
#> $NIE_se
#> [1] NA
#> 
#> $NIE_p
#> [1] NA
#> 
#> $alpha_M
#> [1] NA
#> 
#> $alpha_se
#> [1] NA
#> 
#> $beta_M
#> [1] NA
#> 
#> $beta_M_se
#> [1] NA
#> 
#> attr(,"reason")
#> [1] "COCA mediation regresses W on Y (W ~ y + X + M), placing the outcome on the RHS, which is impossible with a Surv object. COCA mediation is unsupported for survival outcomes."
# all NA (COCA mediation unsupported for survival outcomes)