fit.mult: Fits a multiplicative relative risk model to interval censored data.
Description
Utility function.
The model fitted assumes a piecewise constant baseline rate in
intervals specified by the argument breaks, and a
multiplicative relative risk function.
Usage
fit.mult( y, rates.frame, cov.frame, start )
Arguments
y
Binary vector of outcomes
rates.frame
Dataframe expanded from the original data by
expand.data, cooresponding to covariates for the rate
parameters.
cov.frame
do., but covariates corresponding to the
formula argument of Icens
start
Starting values for the rate parameters. If not supplied,
then starting values are generated.
Value
A list with three components:
ratesA glm object from a binomial model with log-link,
estimating the baseline rates.
covA glm object from a binomial model with complementary
log-log link, estimating the log-rate-ratios
niterNuber of iterations, a scalar
Details
The model is fitted by alternating between two generalized linear
models where one estimates the underlying rates in the intervals, and
the other estimates the log-relative risks.
References
B Carstensen: Regression models for interval censored
survival data: application to HIV infection in Danish homosexual
men. Statistics in Medicine, 15(20):2177-2189, 1996.
CP Farrington: Interval censored survival data: a generalized linear
modelling approach. Statistics in Medicine, 15(3):283-292, 1996.