Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » sci.math.* » sci.stat.edu.independent

Topic: A question on conditional probability!
Replies: 1   Last Post: May 26, 2006 8:16 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View  
Ray Koopman

Posts: 3,383
Registered: 12/7/04
Re: A question on conditional probability!
Posted: May 26, 2006 8:16 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Sticker wrote:
> I have a question, how to calculate the probability as following:
> P(A1 & A2 & A3 | B)?
> Given the condition that event B happens, how to calculate the
> probability of all A1, A2 and A3 happen? Here A1, A2, A3 are
> independent with each other but they are dependent with B separately.
>
> Can I say:
>
> P(A1 & A2 & A3 | B) = P(A1 | B) * P(A2 | B) * P(A3 | B)?


In general, no. Marginal independence does not imply
conditional independence. Look up "Simpson's paradox".




Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.