The survival function describes the probability that a variate  takes on a value greater than a number
 
 (Evans et al. 2000, p. 6).
 The survival function is therefore related to a continuous probability
 density function 
 by
| 
(1)
 | 
so .
 Similarly, the survival function is related to a discrete probability 
 by
| 
(2)
 | 
The survival function 
 and distribution function 
 are related by
| 
(3)
 | 
since probability functions are normalized.
 
         
	    
	
    
