logrankSingleEExact: Helper function computes single component of the exact...

In safestats: Safe Anytime-Valid Inference

Helper function computes single component of the exact logrank e-value

Description

Helper function computes single component of the exact logrank e-value

Usage

logrankSingleEExact(obs0, obs1, y0, y1, thetaS, theta0 = 1, ...)

Arguments

obs0	integer, number of observations in the control group.
obs1	integer, number of observations in the treatment group.
y0	integer, total number of participants in the control group.
y1	integer, total number of participants in the treatment group.
thetaS	numeric > 0 represents the savi test defining (GROW) alternative hypothesis obtained from designSaviLogrank().
theta0	numeric > 0 represents the null hypothesis. Default theta0=1.
...	further arguments to be passed to or from methods.

Value

Returns a list containing at least the following components:

logP0

Log likelihood of Fisher's hypergeometric at the null

logEValueLess

Log likelihood of Fisher's hypergeometric at the alternative

logEValueGreater

Log likelihood of Fisher's hypergeometric at 1/alternative

References

Grünwald, P. D., de Heide, R., & Koolen, W. (2024). Safe testing. Journal of the Royal Statistical Society. Series B (Methodological), 86(5), 1091-1128. (With discussions), https://doi.org/10.1093/jrsssb/qkae011. ter Schure, J., Pérez-Ortiz, M. F., Ly, A., & Grünwald, P. D. (2024). The Safe Logrank Test: Error control under continuous monitoring with unlimited horizon. The New England Journal of Statistics in Data Science, 2(2), 190-214, https://doi.org/10.51387/24-NEJSDS65.

Examples

#'
y0Vector <- c(5, 4, 3, 3, 2, 1)
y1Vector <- c(5, 5, 4, 2, 2, 0)
obs0Vector <- c(1, 1, 0, 1, 0, 1)
obs1Vector <- c(0, 0, 1, 0, 1, 0)

logEValueGreater <- logEValueLess <- vector("numeric", length(y0Vector))

for (i in seq_along(y0Vector)) {
  tempResult <- logrankSingleEExact(obs0=obs0Vector[i], obs1=obs1Vector[i],
                                    y0=y0Vector[i], y1=y1Vector[i],
                                    thetaS=0.7, theta0=1)
  logEValueLess[i] <- tempResult[["logEValueLess"]]
  logEValueGreater[i] <- tempResult[["logEValueGreater"]]
}

eValueLess <- exp(sum(logEValueLess))
eValueLess #1.116161
eValueGreater <- exp(sum(logEValueGreater))
eValueGreater # 0.7665818
eValue <- 1/2*eValueLess + 1/2*eValueGreater
eValue # 0.9413714

safestats documentation built on Sept. 6, 2026, 1:06 a.m.