Re: Statistics

[Tung Pham <ptung@cs.stanford.edu>]

Here is another interesting statistic problem:

	A blood test is 95 percent effective in detecting a certain
disease when it is, in fact, present. However, the test also yields a 
"false positive" result for 1 percent of the healthy persons tested.
(That is if a healthy persion is tested, then , with probability .01,
the test result will imply he or she has the desease.) If .5 percent
of the population actually has the disease, what is the probability a person 
has the desease given that the test result is positive ?


	You will be very suprise to see the result.

Tung