GTSG: Gastrointestinal Tumor Study Group

In coin: Conditional Inference Procedures in a Permutation Test Framework

Gastrointestinal Tumor Study Group

Description

A randomized clinical trial in gastric cancer.

Usage

GTSG

Format

A data frame with 90 observations on 3 variables.

time

survival time (days).

event

status indicator for time: 0 for right-censored observations and 1 otherwise.

group

a factor with levels "Chemotherapy+Radiation" and "Chemotherapy".

Details

A clinical trial comparing chemotherapy alone versus a combination of chemotherapy and radiation therapy in the treatment of locally advanced, nonresectable gastric carcinoma \bibcitepcoin::Stablein_1981.

Results of the procedures by \bibcitetcoin::moreau_1992 and \bibcitetcoin::shen_2000 are presented in the example section.

Note

There is substantial separation between the estimated survival distributions at 8 to 10 months, but by month 26 the distributions intersect.

References

\bibshow

*

Examples

## Plot Kaplan-Meier estimates
plot(survfit(Surv(time / (365.25 / 12), event) ~ group, data = GTSG),
     lty = 1:2, ylab = "% Survival", xlab = "Survival Time in Months")
legend("topright", lty = 1:2,
       c("Chemotherapy+Radiation", "Chemotherapy"), bty = "n")

## Asymptotic logrank test
logrank_test(Surv(time, event) ~ group, data = GTSG)

## Asymptotic Prentice test
logrank_test(Surv(time, event) ~ group, data = GTSG, type = "Prentice")

## Asymptotic test against Weibull-type alternatives (Moreau et al., 1992)
moreau_weight <- function(time, n.risk, n.event)
    1 + log(-log(cumprod(n.risk / (n.risk + n.event))))

independence_test(Surv(time, event) ~ group, data = GTSG,
                  ytrafo = function(data)
                      trafo(data, surv_trafo = function(y)
                          logrank_trafo(y, weight = moreau_weight)))

## Asymptotic test against crossing-curve alternatives (Shen and Le, 2000)
shen_trafo <- function(x)
    ansari_trafo(logrank_trafo(x, type = "Prentice"))

independence_test(Surv(time, event) ~ group, data = GTSG,
                  ytrafo = function(data)
                      trafo(data, surv_trafo = shen_trafo))

coin documentation built on June 30, 2026, 9:06 a.m.