Grouped-time Cox geometry under Efron and exact tie handling

Characterize the population geometry of the least-false Cox coefficient for grouped exit times when tied events are handled using Efron’s method or exact partial likelihood, rather than the Breslow tie rule.

Background

The paper derives the grouped-time population equation and asymptotic geometry only for ceiling aggregation with Breslow handling of tied events. It explicitly notes that Efron and exact partial likelihood lead to different population equations, leaving their coefficient geometry unresolved.