Like so many of the others on this forum, I've had terrible sinus headaches after having a root canal done 3 weeks ago. It started as soon as the Novocaine wore off. It was almost unbearable for the first 2 days. It began around my right eye and nose (the root canal was in my upper right side).
Survival analysis is generally defined as a set of methods for analyzing data where the outcome variable. is the time until the occurrence of an event of interest. The event can be death, occurrence of a disease, marriage, divorce, etc. The time to event or survival time can be measured in days, weeks, years, etc.
The study will certainly record the survival time of each patient (measured from the time of the surgery). This really is the outcome of the study; survival time is the response variable. Now, each patient will get one of the two types of operations; this is a second variable. . .let's call it the procedure variable; it takes one of two possible values, Angioplasty and Bypass.