Determining Sample Size

8.4.4.3 - Determining Sample Size (Rev. 11962; Issued: 04-21-23; Effective: 05-22-23; Implementation: 05-22-23) The size of the sample (i.e., the number of sampling units constituting the sample) will have a direct bearing on the precision of the estimated overpayment, but it is not the only factor that influences precision. It is neither possible nor desirable to specify a minimum sample size that applies to all situations. In addition to the above considerations, real-world economic constraints shall be taken into account. As stated earlier, sampling is used when it is not administratively feasible to review the entire target population. In determining the sample size to be used, the contractor shall also consider its available resources. That does not mean, however, that the resulting estimate of overpayment is not valid, so long as proper procedures for the execution of probability sampling and overpayment estimation have been followed. Some challenges to the validity of the sample that are sometimes made include whether -- (1) The probability sample was chosen and drawn in a statistically appropriate way from the target population or (2) The particular sample size is too small to yield meaningful results. Such challenges are without merit when presented in isolation from any reference to the actual sampling methodology used, and when presented without a complete account of the actual sampling methodology used.