Survival Analysis – Reliability Theory / Human Life – Transistor’s Life (Part 1)

Survival analysis quantifies the uncertainty associated with the mortality of human life. To understand this concept we have to zoom into the human life. Human life is governed by multiple random events. But some aspects of human lives can be totally controlled and are hence of deterministic nature. These are normal day to day activities like waking up at a specific time, going to school at a specific time, activities in school and offices conducted at a specific time, engagement in specific extracurricular activities after school/office and finally going to bed at a specific time. Each individual can exercise some kind of control in the implementation of these activities and also in the time of conduction of these activities. But there are several events where the time of occurrence and its outcome are random in nature. Hence these outcomes and times of occurrence of these outcomes can be described by a random variable. Following examples highlight different shades of human life where probability theory plays a crucial role. We start from the very beginning where the time of birth of an individual is a random variable. Although a date of birth is predicted by a Gynecologist, the exact time of birth (by natural process) cannot be controlled. This time is a continuous random variable. The gender of the child who is the result of this process is also a random variable. If X is a random variable denoting a girl, then X = 0, 1 implies that either a boy or a girl is born out of this process. (To be continued tomorrow)