On nonidentifiability and noninformative censoring for current status data

The event times and examination times that produce current status data are typically assumed to be independent. Here, an increasing sequence of nested models is considered for current status data, namely independence models, 'constant sum' models and models for which the conditional probability of the occurrence of the event prior to the examination time, given the examination time, is nondecreasing in the examination time. In the class of constant sum models, the distribution of the event time is identifiable and the examination times are noninformative. In the class of models with nondecreasing conditional probability, the distribution of the event time is nonidentifiable. Outside this class, the examination times cannot be ignored.