Wednesday, March 29, 2017

Survival Analysis – Reliability Theory / Human Life – Transistor’s Life (Part 4)



Summary of Human Life in Terms of Random Variables
Discrete Random Variables:
1         Gender of an individual at the time of birth
2        No of time he/she falls sick in his/her entire lifetime
3         No of children born by him/her in the entire lifetime
4           No of girls born among the total children born
5         No of jobs changed in his/her entire lifetime
Continuous Random Variables:
1           Time of birth of an individual
2          Time of illness
3          Time between two consecutive illnesses
4           Time of recovery from illness
5          Time of marriage
6           Time of birth of children
7            Time between two consecutive births
8           Age  at the time of death

In all these events memory plays an important role. For example the time between two consecutive births is at least 9 months. The probability of time of second attack of severe illness is the highest when this time is closer to the time of recovery from first illness. This is due to the probability of relapse of a disease. So failure rate or force of mortality is affected by memory. Failure rate is higher for very old ages and very young ages.  But this is not true in the case of electronic devices, batteries etc. This  will be discussed tomorrow in the discussion on reliability theory.

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