<正>1. Introducton Survival analysis concerns the tme from a well-defnedorigin to some event of interest, such as the tme fromsurgery to death of a cancer patent, the tme fromwedding to divorce, and the tme between the frst andsecond suicide atempts. Although originated in researchon the actve lifetme of light bulbs and other electricdevices, modern applicatons of survival analysis includemany non-survival events. Thus, survival analysis may bemore appropriately called the tme-to-event analysis.