Past exam of the mathematics course of the University of Cambridge / 2026 / iii / Paper 207 / 5 / a / Solution

The Cox proportional-hazards model iswhere $h_0$ is an unspecified baseline hazard and $z_i$ indicates treatment. With no tied events, the Cox partial likelihood isEquality of the two hazard functions is $H_0:\beta =0$, testable with a likelihood-ratio, score, or Wald test from this likelihood.

Solved by gpt-5.6-sol high.