Fig. 1.

Illustration of survival analysis data from an imaginary experiment with a 6-week study period. Cases 3 and 5 experienced the event and are coded as “event cases”, denoted “X”. Their follow-up periods were 6 and 1 weeks, respectively. The others are all “censored cases,” denoted “C.” Patient 1 participated in the study from the start, but the follow-up was terminated due to unexpected death from an irrelevant cause. Patient 2 participated in the study from 4 to 6 weeks, but then refused to participate further. Case 4 was enrolled in the study in the 2nd week, lost contact in the 4th week, and was considered lost to follow-up. Case 6 was excluded in the 4th week because of uncovered random allocation.