Manufacturing Organizations Find the Following Sampling Strategies Useful

QM 1123 CLMN John Vandenbemden feature image — *Image Source: iStock/Getty Images Plus*

Statistical sampling has been a very popular topic in recent years. The sampling strategy is an important part of statistical sampling. Manufacturing organizations find the following sampling strategies to be useful:

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QM 1123 CLMN John Vandenbemden Random sampling — (Simple) Random sampling (SRS) - Each item in the lot has the same probability to be selected for the sample.

QM 1123 CLMN John Vandenbemden Convenience sampling — (Simple) Random sampling (SRS) - Each item in the lot has the same probability to be selected for the sample.

The examples illustrate the different sampling strategies for a two-dimensional population, such as products spread open for a drying process. There is no statistical guidance on which sampling strategy is superior to the others. ISO 2859-4 (1999) advises: “The items selected for the sample shall be drawn from the lot by simple random sampling …. However, when the lot consists of sub-lots or strata, identified by some rational criterion, stratified sampling shall be used in such way that the size of the subsample from each sublot or stratum is proportional to the size of that sublot or stratum”.

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John Vandenbemden currently sits on the ASQ Standards Committee as the Inspection Division representative. He is a voting member of TC 176 and chair of the SC5, USTAG 69 and and audits for SRI and Quality Auditing. Vandenbemden is past-chair of the ASQ Inspection Division. For more information, email [email protected].

Vandenbemden is also the 2022 Quality Professional of the Year.