Re: Statistics

[Tuan V Nguyen <t.nguyen@garvan.unsw.edu.au>]

Hello Tu`ng & friends,


At 05:07 PM 7/15/97 -0500, you wrote:
>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 ?
>

        This is a total probability (Bayesian) problem. These days, any good
textbook has feature on Bayes' method, since it is very common in medical
statistics. I think you have to explain to the audience here what do you
mean by the word "false positive", "false negative", "specificity",
"sensitivity", etc. I am sure there are people here want to know/learn more
about these terminologies.

        Tuan