我正在病例对照研究中用权重来估计生存率。因此，所有案例的权重都等于 1。在绘制估计曲线并将其与未加权估计进行比较时，我注意到案例的 KM 曲线不重叠。
这是“survival”包中的数据代码。
library(dplyr)
library(tidyverse)
library(survival)
library(broom)
library(WeightIt)
library(survey)
a <- survival::ovarian
#Calculation of weghts:
weights <- WeightIt::weightit(rx ~ age + ecog.ps + resid.ds, int = T, estimand = "ATT", data = a, method = "glm" , stabilize = F, missing = "saem")
a$weights <- weights$weights
a$ps <- weights$ps
design <- svydesign(ids = ~ 1, data = a, weights = ~weights)
KM_PFS <- survfit(Surv(futime, fustat > 0)~rx, a) # KM naive
KM_PFS_w_TT <- survfit(Surv(futime, fustat > 0)~rx, a, …