epiR (version 1.0-10)

epi.insthaz: Instantaneous hazard estimates based on Kaplan-Meier survival estimates

Description

Compute the instantaneous hazard on the basis of a Kaplan-Meier survival function.

Usage

epi.insthaz(survfit.obj, conf.level = 0.95)

Arguments

survfit.obj

a survfit object, computed using the survival package.

conf.level

magnitude of the returned confidence interval. Must be a single number between 0 and 1.

Value

A data frame with three elements: time the observed failure times, est the proportion of the population failing per unit time, lower the lower bounds of the confidence interval, and upper the upper bounds of the confidence interval.

Details

Computes the instantaneous hazard of failure, equivalent to the proportion of the population failing per unit time.

References

Venables W, Ripley B (2002). Modern Applied Statistics with S, fourth edition. Springer, New York, pp. 353 - 385.

Singer J, Willett J (2003). Applied Longitudinal Data Analysis Modeling Change and Event Occurrence. Oxford University Press, London, pp. 348.

Examples

# NOT RUN {
require(survival)

ov.km <- survfit(Surv(futime, fustat) ~ 1, data = ovarian)
ov.haz <- epi.insthaz(ov.km, conf.level = 0.95)
ov.shaz <- data.frame(
   time = lowess(ov.haz$time, ov.haz$lower, f = 0.50)$x,
   est =  lowess(ov.haz$time, ov.haz$est, f = 0.50)$y,
   low =  lowess(ov.haz$time, ov.haz$lower, f = 0.50)$y,
   upp =  lowess(ov.haz$time, ov.haz$upper, f = 0.50)$y)

plot(x = ov.haz$time, y = ov.haz$est, xlab = "Days", 
  ylab = "Instantaneous hazard", type = "b", pch = 16, ylim = c(0, 0.02))
lines(x = ov.shaz$time, y = ov.shaz$est, 
   lty = 1, lwd = 2, col = "red")
lines(x = ov.shaz$time, y = ov.shaz$low, 
   lty = 2, lwd = 1, col = "red")
lines(x = ov.shaz$time, y = ov.shaz$upp, 
   lty = 2, lwd = 1, col = "red")

# }
# NOT RUN {
library(ggplot2)

ggplot(data = ov.haz, aes(x = time, y = est)) +
   geom_line() + 
   geom_line(data = ov.shaz, aes(x = time, y = est), 
      lty = 1, lwd = 1.0, col = "red") + 
   geom_line(data = ov.shaz, aes(x = time, y = low), 
      lty = 2, lwd = 0.5, col = "red") +
   geom_line(data = ov.shaz, aes(x = time, y = upp), 
      lty = 2, lwd = 0.5, col = "red") +
   xlab(label = "Days") +
   ylab("Instantaneous hazard") +
   ylim(0, 0.02)
# }
# NOT RUN {
# }