Solution
= Solution
At the month-48 analysis, the observed time from treatment start is:
$$
\begin{array}{c|cccccc}
\text{patient}&A&B&C&D&E&F\\ \hline
\text{time}&26&7&13&37&7&27\\
\text{status}&\text{death}&\text{death}&\text{death}&\text{censored}&\text{death}&\text{death}.
\end{array}
$$
For example, patient D contributes $48-12+1=37$ months. This is <right censoring> at a common calendar data cutoff but with staggered treatment entry.