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ICBayes (version 1.2)

case2probit: Probit model for general interval-censored data

Description

Fit probit model to general interval-censored data. Use MCMC method to estimate regression coefficients, baseline survival, and survival function at user-specified covariate values.

Usage

case2probit(L, R, status, xcov, x_user, order, m0,
	    v0, a_eta, b_eta, knots, grids, niter, seed)

Arguments

L

a numeric vector of left timepoints of observed time intervals.

R

a numeric vector of right timepoints of observed time intervals.

status

a vector of censoring indicators: 0=left-censored, 1=interval-censored, 2=right-censored.

xcov

a matrix of covariates, each column corresponds to one covariate.

x_user

a vector of user specified covariate values.

order

degree of I-splines (b_l) (see details). Recommended values are 2-4.

m0

mean of normal prior for gamma_0.

v0

precision of normal prior for gamma_0.

a_eta

shape parameter of Gamma prior for gamma_l (see details).

b_eta

rate parameter of Gamma prior for gamma_l (see details).

knots

a sequence of points to define I-splines.

grids

a sequence of points where baseline survival function is to be estimated. Default is minimum observed time points.

niter

total number of iterations of MCMC chains.

seed

a user specified random seed, default is NULL.

Value

a list containing the following elements:

parbeta

a niter by p matrix of MCMC draws of beta_r, r=1, ..., p.

parsurv0

a niter by length(grids) matrix, each row contains the baseline survival at grids from one iteration.

parsurv

a niter by length(grids)*G matrix, each row contains the survival at grids from one iteration. G is the number of sets of user-specified covariate values.

parfinv

a niter by n matrix, each row contains the inverse PDF of observed interval-censored data from one iteration. This is used for computing LPML later.

grids

a sequence of points where baseline survival is estimated.

Details

The baseline function is modeled by a linear combination of I-splines:

gamma_0+sum_{l=1}^{k}(gamma_l*b_l).

Regression coefficient vector beta is sampled from a multivariate normal distribution. For more information, please see reference.

References

Lin, X. and Wang, L. (2009). A semiparametric probit model for case 2 interval-censored failure time data. Statistics in Medicine 29 972-981.