survivor function
Let $Y$ be a random variable^{} with cumulative probability distribution function ${F}_{Y}(y)$. Then the survivor function $S(y)$ is defined to be:
$$S(y)=1{F}_{Y}(y)=P(Y\ge y).$$ 
The random variable $Y$ is often called the survival time.
The survivor function is the probability of survival beyond time $Y=y$.
Examples. The three most commonly used distribution functions^{} for survival time are:

1.
exponential distribution^{} (http://planetmath.org/ExponentialRandomVariable), with $S(y)=\mathrm{exp}(\gamma y).$

2.
Weibull distribution^{}, with $S(y)=\mathrm{exp}({y}^{\gamma})$ using the standard Weibull distribution.

3.
extremevalue distribution, with $S(y)=\mathrm{exp}(\mathrm{exp}({\displaystyle \frac{y\alpha}{\beta}})).$
Title  survivor function 

Canonical name  SurvivorFunction 
Date of creation  20130322 14:27:43 
Last modified on  20130322 14:27:43 
Owner  CWoo (3771) 
Last modified by  CWoo (3771) 
Numerical id  6 
Author  CWoo (3771) 
Entry type  Definition 
Classification  msc 62N99 
Classification  msc 62P05 
Defines  survival time 