frailtyHL: A Package for Fitting Frailty Models with H-likelihood.

We present the frailtyHL package for fitting semi-parametric frailty models using hlikelihood. This package allows lognormal or gamma frailties for random-effect distribution, and it fits shared or multilevel frailty models for correlated survival data. Functions are provided to format and summarize the frailtyHL results. The estimates of fixed effects and frailty parameters and their standard errors are calculated. We illustrate the use of our package with three wellknown data sets and compare our results with various alternative R-procedures. [ABSTRACT FROM AUTHOR]