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2025-01-12 00:52:51 +08:00
R Under development (unstable) (2020-03-27 r78086) -- "Unsuffered Consequences"
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> library(survival)
> options(na.action=na.exclude, contrasts=c('contr.treatment', 'contr.poly'))
>
> # Verify stratified fits in a simple way, but combining two data
> # sets and doing a single fit
> #
> aeq <- function(x,y) all.equal(as.vector(x), as.vector(y))
>
> tdata <- data.frame(time=c(lung$time, ovarian$futime),
+ status=c(lung$status-1, ovarian$fustat),
+ group =rep(0:1, c(nrow(lung), nrow(ovarian))))
> fit1 <- survreg(Surv(time, status) ~ 1, lung)
> fit2 <- survreg(Surv(futime, fustat) ~ 1, ovarian)
> fit3 <- survreg(Surv(time, status) ~ group + strata(group), tdata)
>
> aeq(c(fit1$coef, fit2$coef-fit1$coef), fit3$coef)
[1] TRUE
> aeq(c(fit1$scale, fit2$scale), fit3$scale)
[1] TRUE
> aeq(fit1$loglik[2] + fit2$loglik[2], fit3$loglik[2])
[1] TRUE
>
> #
> # Test out the cluster term in survreg, which means first a test
> # of the dfbeta residuals
> # I also am checking that missing values propogate
> test1 <- data.frame(time= c(9, 3,1,1,6,6,8),
+ status=c(1,NA,1,0,1,1,0),
+ x= c(0, 2,1,1,1,0,0),
+ id= 1:7)
> fit1 <- survreg(Surv(time, status) ~ x, cluster = id, test1)
> fit2 <- survreg(Surv(time, status) ~ x + cluster(id), test1) #old form
> all.equal(fit1, fit2)
[1] TRUE
>
> db1 <- resid(fit1, 'dfbeta')
> ijack <-db1
> eps <- 1e-7
> for (i in 1:7) {
+ temp <- rep(1.0,7)
+ temp[i] <- 1-eps
+ tfit <- survreg(Surv(time, status) ~ x, test1, weight=temp)
+ ijack[i,] <- c(tfit$coef, log(tfit$scale))
+ }
> ijack[2,] <- NA # stick the NA back in
> ijack <- (rep(c(fit1$coef, log(fit1$scale)), each=nrow(db1)) - ijack)/eps
> all.equal(db1, ijack, tolerance=eps)
[1] TRUE
> all.equal(t(db1[-2,])%*% db1[-2,], fit1$var)
[1] TRUE
>
> # This is a harder test since there are multiple strata and multiple
> # obs/subject. Use of enum + strata(enum) in essenence fits a different
> # baseline Weibull to each strata, with common coefficients for rx, size, and
> # number.
> fit1 <- survreg(Surv(stop-start, event) ~ rx + size + number +
+ factor(enum) + strata(enum), data=bladder2)
>
> db1 <- resid(fit1, type='dfbeta', collapse=bladder2$id)
> ijack <- db1 # a matrix of the same size
> for (i in 1:nrow(db1)) {
+ twt <- rep(1., nrow(bladder2))
+ twt[bladder2$id==i] <- 1-eps
+ tfit <- survreg(Surv(stop-start, event) ~ rx + size + number +
+ factor(enum) + strata(enum), data=bladder2,
+ weight=twt)
+ ijack[i,] <- c(coef(tfit), log(tfit$scale))
+ }
> ijack <- (rep(c(fit1$coef, log(fit1$scale)), each=nrow(db1)) - ijack)/eps
> all.equal(db1, ijack, tolerance=eps*2)
[1] TRUE
>
>
> proc.time()
user system elapsed
1.207 0.065 1.262