# Log-rank test returning error code [on hold]

When trying to perform a log-rank test using the Survival package in R I run into the following error:

Error in survdiff(Surv(tstart, tstop, event == 1) ~ group, data = df) :
Right censored data only

As an example with this dummy data set:

id <- c(rep("1", 10), rep("2", 10), rep("3", 10), rep("4", 10), rep("5", 10))
age <- c((15:24), (35:44), (45:54), (55:64), (40:49))
event <- c(rep("0", 10),
0, 0, 0, 0, 0, 0, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
0, 0, 0, 1, 1, 1, 1, 1, 1, 1,
0, 0, 0, 2, 2, 2, 2, 2, 2, 2)
group <- c(rep("a", 14), rep("b", 4), rep("a", 6), rep("b", 3), "a", "b", "b", rep("a", 4), rep("c", 6), rep("d", 4), rep("a", 6))

df <- data.table(id, age, event, group)
df$$tstart <- integer(0) df$$tstop <- df$$age df[, tstart := shift(tstop), by = id] df$$tstart <- ifelse(is.na(df$$tstart), 14, df$$tstart)

The following code works fine:

survdiff(Surv(tstop, event == 1) ~ group, data = df)

however this returns an error code:

survdiff(Surv(tstart, tstop, event == 1) ~ group, data = df)

I've been using the start/stop format for the kaplan meier curve and cox regression, and it's working fine; however the log-rank test code does not run as expected. Does anyone know how to deal with this error?

Thanks.

## put on hold as off-topic by jbowman, Michael Chernick, Peter Flom♦12 hours ago

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• The error is telling you that only right censored data is allowed in this scenario, so no start and stop method for this log-rank test. Also using event==1 inside the formula is weird. – user2974951 Jan 8 at 14:00