Description Usage Arguments Details Value Note Author(s) References See Also Examples

This is the function called by `rld`

that do the actual computation.

1 |

`X` |
a design matrix created based on the input formula. |

`C` |
a vector containing censoring times. |

`delta` |
a vector contatining censoring status in which"1" denotes failure, "0" denotes right-censoring. |

`initial` |
a vector containing initial values for the paramters to be optimized over. |

`lower` |
a vector containing lower bound values for the paramters to be optimized over. |

`upper` |
a vector containing upper bound values for the paramters to be optimized over. |

`frailty` |
logical value: If TRUE, a discrete-time survival model with random effects will be used. |

`optim`

is used to maximize the log-likelihood function. Method "L-BFGS-B" is that of Byrd et. al (1995) which allows box constraints, that is each variable can be given a lower and/or upper bound.

`coefficients` |
parameter estimates. |

`hessian` |
hessian matrix. |

`LikFunValue` |
log-likelihood value. |

Don't use this function when you are not familiar with the whole computational procedure.

Bin Yao, Ying Huang and Chaeryon Kang

Kang, C., Huang, Y., and Miller, C. (2015). A discrete-time survival model with random effects for designing and analyzing repeated low-dose challenge experiments. *Biostatistics*, 16(2): 295-310.

Byrd, R.H., Lu, P. Nocedal, J. and Zhu, C. (1995). A limited memory algorithm for bound constrained optimization. *SIAMJ. Scientific Computing*, 16, 1190-1208.

1 2 3 4 5 6 7 8 9 10 11 12 13 | ```
data(SampleData)
newdata <- transdata(data = SampleData, ndlevel = 3, nexposure = c(10, 10, 2))
formulaexp <- survival::Surv(time, delta)~factor(dose)+trt+I(I(dose==3)*trt)
designmat <- model.matrix(formulaexp, data = newdata)
time <- SampleData$time
status <- SampleData$delta
inival <- rep(0.5, 6)
lwrval <- c(rep(-Inf, 5), 0.01)
uprval <- rep(Inf, 6)
frailty <- TRUE
rld.fit(X = designmat, C = time, delta = status, initial = inival,
lower = lwrval, upper = uprval, frailty = frailty)
``` |

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