Solution
= Solution
<Right censoring> occurs when a subject's exact failure time $T$ is unobserved but it is known that $T>C$, where $C$ is the censoring time. The observed pair is $U=\min(T,C)$ and $\Delta=\mathbf1_{\{T\le C\}}$. For example, a living participant at study closure contributes a survival lower bound rather than a recorded death at closure. <Right censoring> differs from simply omitting the subject: time spent in the <risk set> remains informative.