Terminal censoring and survival-mean identifiability

If the last observed follow-up is a censoring time and the Kaplan–Meier estimator remains positive there, the observed curve does not determine the remaining tail area. Many possible completions give different full means, including finite and infinite ones. A horizontal plotting extension is not proof that the true mean is infinite. If the final risk set is exhausted by events, its Kaplan–Meier estimator factor is zero and the conventional fitted curve has finite area. This includes a unique last individual having an event, but an event tied with terminal censoring can leave a positive fitted survivor value when events are processed before censoring. The random endpoint still does not establish a population support bound. A restricted mean survival time avoids unsupported tail completion.