Sequential Statistics

In reliability problems the parameter p which is the probability that one random variable is stochastically larger than the other is of much interest.
Sequential confidence interval for p=P(X
Let D i =Y i ?X i , D n = Y n ? X n ,
where Y n and X n denote means of samples of size n. Then, it is well known that p= ? ( ? D / ? D ) where ? D =E(Y ?X),
denotes the variance of (Y ?X). Whatever be the covariance structure of X and Y, a reasonable estimate of p is
. Then, we have the following result. For the sake of simplicity, we shall suppress all the subscripts in ?, ?, s and
.
Let a 2=(1+ ? 2/2 ? 2) and
. Then, we have
where the subscript n in D n is suppressed for the sake of implicity.
Let
. First we will show that
Toward this, write
where t lies between D and ?. However, since D converges to ?