# library(survival)

plot(survfit(aml.maint)) 			# plot K-M 
summary(survfit(aml.maint)) 			# show K-M computations

print(survfit(aml.maint),show.rmean=T)	# K-M based inference
a <- summary(survfit(aml.maint))


#  S(13) estimation and CI

10/11 * 9/10
cumprod(  (a$n.risk -a$n.event) /a$n.risk)
a$surv[2] * sqrt( 1/110 + 1/90)

(mn <- log(0.818))
(sd <- sqrt(1/110 + 1/90))

(ll <-  exp( mn - qnorm(0.975)*sd))
(ul <-  exp( mn + qnorm(0.975)*sd))

summary(survfit(aml.maint,conf.type="plain"))


# Restricted mean estimation

print(survfit(aml.maint),show.rmean=T)
a

t.i    <- c(0,a$time,161)
surv.i <- c(1,a$surv)
sum(diff(t.i) * surv.i)