ABSTRACT
A sample is the key factor determining whether the results have any meaning or not, regardless of whether it is being used for a customer survey; for an opinion poll, for testing a food additive, for comparing two methods or machines, for auditing a set of transactions or procedures, for collecting evidence for a regulatory proceeding, for measuring the quality of performance of an employee or supplier, for estimating the level of air or water or radioactive pollution, or for measuring the efficacy of a drug.
