library(Greg)
data("melanoma", package = "boot", envir = environment())
library(dplyr)
melanoma <- mutate(melanoma,
status = factor(status,
levels = 1:3,
labels = c("Died from melanoma",
"Alive",
"Died from other causes")),
ulcer = factor(ulcer,
levels = 0:1,
labels = c("Absent", "Present")),
time = time/365.25, # All variables should be in the same time unit
sex = factor(sex,
levels = 0:1,
labels = c("Female", "Male")))
library(survival)
model <- coxph(Surv(time, status == "Died from melanoma") ~ sex + age,
data = melanoma
)
nl_model <- addNonlinearity(model, "age",
spline_fn = "pspline",
verbal = TRUE,
workers = FALSE
)
# Note that there is no support for nonlinearity in this case
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