Buying Software with Exact Confidence.

We derive several new results which may be helpful to the buyers of software, testing for faults, or to the buyers of large lots, screening for defectives. Specifically, suppose that a fixed but unknown number n of faults or defectives remain before testing. In the testing phase they are observed at random times, T sub 1, T sub 2, ..., which are independent and identically distributed. Since testing is usually an on-going activity, this distribution is typically known. Under this assumption we derive a stopping criterion that guarantees that the tested software has no more than m defectives remaining with an exact probability 1 - alpha for any prespecified level alpha and integer m