Economic Evaluation of ISO 2859 Acceptance Sampling Plans Used with Rectifying Inspection of Rejected Lots

ABSTRACT

To conduct acceptance sampling, companies often use plans that are determined by easy-to-use standards. However, these standards do not take quality costs directly into account. Motivated by the case of a Greek company, which uses the Greek equivalent to the ISO 2859 (1974) for the quality control of its incoming raw materials, this article aims to evaluate the single-sampling plans recommended by the latest update of ISO 2859 from an economic point of view. The evaluation shows that the use of standards rarely leads to satisfactory economic results. Therefore, simple rules for the economical use of the standard are provided.

KEYWORDS:

• acceptance sampling
• economic design
• quality cost
• sampling plan
• statistical quality control

ACKNOWLEDGMENTS

The authors thank Dimitris Hatzinikolaou for his valuable contribution to this article. The authors are also grateful to the two reviewers for their valuable remarks that contributed significantly to the improvement of the article.

Notes

¹In order to design this pdf, we first created a normal pdf using the same mean and variance with the uniform pdf (0.15–4%) and then we turncated the areas below 0.15% and above 4%. We computed the necessary probabilities by dividing the probabilities of the initial normal pdf with the probability corresponding to the truncated area; i.e., between 0.15 and 4%.

²Note that the quality of lots may not change dramatically during time in our study, but it is not constant either, since it is assumed to follow a specific pdf. If the fraction nonconforming p were assumed to be constant, then acceptance sampling would be redundant. On the other hand, if it changed dramatically during time, then the use of the switching and/or skip-lot procedures would be essential.

is the average probability of accepting a lot when the fraction nonconforming p is distributed according to ϕ(p).