Survival Analysis – Reliability Theory / Human Life – Transistor’s Life (Part 2)

I am continuing yesterday’s discussion. So the beginning of human life is a playground of probability where the time of birth can be described by a continuous random variable and the outcome (gender/number) are discrete random variables. Similarly, the number of times that individual becomes seriously ill in his entire life time, so that he has to take more than two days leave from his school/office is a discrete random variable, say Y. Then Y = 0, 1, 2, ….n ; implying that he can be seriously ill zero times, once, twice and so on.   This random variable is dependent on the health status of the individual. For a healthy individual the lower values of Y will have high probabilities in contrast to a physically weak individual.  No of sick leaves that he has to take from his school/office is also a discrete random variable. Z = 3, 4, 5, …,m; here we have defined serious illness as illness where number of sick leaves taken from school/office is more than two days. The time between two consecutive illnesses is a continuous random variable. For a physically weak individual smaller time between two consecutive illnesses will have higher probability in contrast to healthy individual.  Healthy individual tend fall seriously ill very less frequently and hence the time between two consecutive illnesses are longer with a higher probability. The time of outbreak of an illness for any individual is also a continuous random variable. (To be continued tomorrow).