Approximations for negative binomial sums have been given by several
authors. Bartko [1] considered five such approximations. Although the first
four leave something to be desired, the last one (called the Camp-Paulson
approximation) seems to be very good. However, considerable arithmetic is
involved requiring a cube root, a 2 power, and a square root to yield an entry
for the standard normal table. Peizer and Pratt [5] also give an approximation
based upon a standard normal entry. Again the arithmetic is unattractive
requiring the use of square roots and an auxilliary table. The objective of this
paper is to give an approximation which is simple to apply and sufficiently
accurate for most practical purposes.