Search All of the Math Forum:

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

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: Beta distributions in multiple coin problem
Replies: 1   Last Post: Jul 3, 2013 4:14 PM

 Messages: [ Previous | Next ]
 Donald Lockwood Posts: 1 Registered: 6/28/13
Beta distributions in multiple coin problem
Posted: Jun 28, 2013 3:36 PM

Hi

In the classical coin toss problem, one can estimate the distribution of \theta (by theta I mean that if \theta=0.5, the coin is unbiased) from an experiment in which one observes m faces from N tosses. If one assumes total ignorance (Prior=Beta(1,1)) then the posterior is simply B(m+1,N-m+1). So far so good.

I have a generalization that I don't know how to solve it. The idea is that we have two two coins. We toss the first one (whose \theta is known). If it's a face then a add a mark in the X category. If it's a tail, then I throw another (now biased) coin: face, I add a mark in category Y; tail, nothing happens.

My question is, if I observe a sequence of X's and Y's (but I don't know the number of tosses of the first coin), what's the posterior distribution (for its \theta) of the second coin? I don't see how to solve it...and it might have interesting applications in message communications.