Estimated survival functions and 95% confidence bands over [0, 30] months, as averages over 100 simulated subcohorts, for a 35-year-old individual in the zidovudine arm with symptomatic HIV infection, hemophilia, and baseline CD4 count of 200. The solid, dotted, and dashed lines correspond to the Self & Prentice, the first of Chen & Lo, and the second of Chen & Lo methods, respectively.