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sonney32

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A manager wants to start drug testing at work, and he wants to find out how accurate the test truly are. Suppose a drug test 99% accurate. This means, the probability that the test is positive given that the person does drugs is 99%. Likewise, the probability that the test is negative given that the person is a non drug user is 99% also. The probably that people do drugs in the workforce is .5%. Using the Bayes' Theorem find the probability of

What is the probability that an employee is a drug user given the test is positive?


What is the probability that an employee is a drug user given the test is negative?


I could really use some guidence on figuring these questions out
Thanks
 
sonney32 said:
A manager wants to start drug testing at work, and he wants to find out how accurate the test truly are. Suppose a drug test 99% accurate. This means, the probability that the test is positive given that the person does drugs is 99%. Likewise, the probability that the test is negative given that the person is a non drug user is 99% also. The probably that people do drugs in the workforce is .5%. Using the Bayes' Theorem find the probability of

What is the probability that an employee is a drug user given the test is positive?


What is the probability that an employee is a drug user given the test is negative?


I could really use some guidence on figuring these questions out
Thanks
Click to expand...

To start with:

What is Bayes' theorem - and how you would use it for this problem?

Please share your work with us, indicating exactly where you are stuck - so that we may know where to begin to help you.
 
I don't have much done on this problem. I need help using the formula to get the answer. This is what I have so far
.005 do drugs in the workforce, and .995 do not do drugs in the workforce

.99 is accurate and .01 is not accurate.
.99 for non drug user and .01 will show up pos for non drug user.

I am just not sure how to put these numbers together using the Bayes' Theorem.

What is the probability that an employee is a drug user given teh test is positive?
would I start by p(.005/.99) ??? not sure

What is the probability that an employee is a drug user given that the test is negative?
p(.01/.05)

Not sure how to plug the numbers in.
Thanks for the help
 
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