Inference: Changepoint models
Changepoint models are considered for three situations in which the models allow departures from proportional hazards to be approximated in a simple way. The first situation is a so-called time-covariate qualitative interaction (O'Quigley and Pessione 1991) or crossing hazards problem. The second situation considers a decline in regression effect that is modeled by a sudden change in effect at some unknown time point (O'Quigley and Natarajan 2004). The third situation, common in prognostic modeling, deals with inference when we wish to simplify a continuous covariate into two classes, above and below some threshold. The results of Davies (1977, 1987) are particularly useful and the conditions under which these results can be applied are described.
KeywordsBootstrap Sample Bootstrap Distribution Acute Graft Versus Host Disease Bootstrap Repetition Cytomegalovirus Pneumonia
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