1pbetat=function(p0,prob,ab,data)
2{
3#
4# PBETAT Performs a test that a proportion is equal to a specific value.
5#	PBETAT(P0,PROB,AB,DATA) gives a vector of the Bayes factor and
6#	the probability of the hypothesis P=P0, where P0 is the proportion
7#	value to be tested, PROB is the prior probability of the hypothesis,
8#	AB is the vector of parameters of the beta density under the
9#	alternative hypothesis, and DATA is the vector of numbers of
10#	successes and failures.
11#------------------------
12# Written by Jim Albert
13# albert@bgnet.bgsu.edu
14# November 2004
15#------------------------
16
17a=ab[1]; b=ab[2]
18s=data[1]; f=data[2]
19
20lbf=s*log(p0)+f*log(1-p0)+lbeta(a,b)-lbeta(a+s,b+f)
21
22bf=exp(lbf)
23post=prob*bf/(prob*bf+1-prob)
24
25return(list(bf=bf,post=post))
26
27}
28