Developing Formulas for Setting an Improved Double Sampling Plan

Abstract

To facilitate the derivation, two-stage fraction non-conforming acceptance sampling plans (with their operations characteristics curves passing through two predetermined points) were traditionally derived under conditions that restricted the relationships between the sample sizes and acceptance numbers of both stages. Removing those restrictions, and applying computerized search procedures in the solution space, improved sampling plans were derived with lower average sample sizes. The reduction in the average sample sizes amounted up to 31.41% and averaged around 7.48%. To facilitate the use of improved average-sample-number reduced sampling plans for unpublished parameter combinations, approximation formulas were developed using regression analysis. Their use allows a reduction of 4% in the Average Sample Number.

Key Words:

• Average sample number
• double sampling plan
• two-staged sampling plan

Additional information

Notes on contributors

Yair Sagiv

Shaul P. Ladany is a graduate of the Technion, Israel Institute of Technology in Mechanical Engineering. He received his B.Sc. degree in 1960, M.Sc. degree in 1961, Graduate Diploma in Business Administration from the Hebrew University, Jerusalem in 1964, and Ph.D. degree from Columbia University, New York in 1968. He is a faculty member of the Department of Industrial Engineering and Management, Ben-Gurion University since 1975, ex-departmental chairman, Chair-holding Full Professor since 1984, and Head of the University Entrepreneurship Center. He held visiting appointments at Columbia University, Rutgers, City University of New York, Temple, Tel-Aviv University, University of Cape-Town, Science Center Berlin, Georgia Tech., Emory, University of California, Irvine, Singapore University, and CSIRO, Melbourne. He has published over 10 books and 100 scientific refereed articles on various operations-management and operations research topics, and holds 8 U.S. Patents. As an amateur athlete in Race-Walking, he won the 100Km World Championship, and set the 50-Mile World Record (both in 1972). He competed in 1968 Mexico and 1972 Munich Olympic Games, won 7 USA National Championships and National Championships in Belgium, Switzerland, South-Africa, and Israel. He is still active in research and sports.

Shaul P. Ladany

Yair Sagiv is a graduate of Ben-Gurion University in Industrial Engineering specializing in Information Systems. He received his B.Sc. in 2002, and M.Sc. in 2005. His research interests include Statistical Quality Control.