Description Usage Arguments Details Value References Examples
Fit the semiparametric marginal proportional hazards mixture cure (PHMC) model for clustered failure time data. The function is based on the methods proposed by Peng et al. (2007) and Niu and Peng (2013).
1 2 |
formula |
a formula expression, of the form |
cureform |
a formula expression, of the form |
data |
a data frame in which to interpret the variables named in the |
id |
a vector which identifies the clusters. The length of |
corstr |
a character string specifying the correlation structure. The following are permitted: |
Var |
If it is TRUE, the program returns Std.Error by the sandwich method. By default, |
stdz |
If it is TRUE, all the covariates in the |
boots |
If it is TRUE, the program returns Std.Error by the bootstrap method. By default, |
nboot |
the number of bootstrap samples. The default is |
esmax |
specifies the maximum iteration number. If the convergence criterion is not met, the ES iteration will be stopped after |
eps |
tolerance for convergence. The default is |
The semiparametric marginal PHMC model is considered in this function. For cure rate, a logistic regression model is employed and the probability of being cured is given by (1+\exp(γ Z))^{(-1)}. For uncured subject, the failure time is modeled by the semiparametric proportional hazards model. A covariate can be used either in formula
or in cureform
or in both. When corstr = independence
, the model parameters are estimated by the expectation-maximization (EM) algorithm and the standard error estimates are obtained from sandwich variance formula based on Peng et al. (2007). When corstr = exchangeable
, stdz = TRUE
and boots = TRUE
, the model parameters are estimated by the expectation-solution (ES) algorithm and the standard error estimates are obtained from bootstrap variance formula based on and Niu et al. (2013).
An object of class geecure2
is returned. It can be examined by print.geecure2()
.
Peng, Y., Taylor, J. M. G., and Yu, B. (2007) A marginal regression model for multivariate failure time data with a surviving fraction. Lifetime Data Analysis, 13: 351-369.
Niu, Y. and Peng, Y. (2013) A semiparametric marginal mixture cure model for clustered survival data. Statistics in Medicine, 32: 2364-2373.
1 2 3 4 5 6 | # Example. Fit the marginal semiparametric PHMC model for the bmt data.
data(bmt)
geebmtind2 <- geecure2(Surv(T2, d3) ~ Z8, cureform = ~ Z8, data = bmt, id = bmt$Z9,
corstr= "independence")
geebmtexch2 <- geecure2(Surv(T2, d3) ~ Z8, cureform = ~ Z8, data = bmt, id = bmt$Z9,
corstr= "exchangeable", stdz = TRUE, Var = FALSE)
|
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