The Square Root of N Plus One Sampling Rule

In the pharmaceutical industry, bulk product characteristics are routinely tested to determine whether the product meets in-house quality assurance specifications. Raw or processed materials are frequently stored in drums or containers. In these instances, one must know how to choose a representative sample that exhibits characteristics similar to those processed by the population as a whole. The common method in statistical practices is choosing a simple random sample from the population.

Journal: 
Pharmaceutical Technology MAY 2003