OPSEARCH,V01: 45, No.1, 2008 0030-3887/00 $ 5.00+0.00
© Operational Research Society of India
Optimum Skiplot Sampling Plans Using Spread Sheets
P. Lavanya Kumari
S.P. WDegree College, Tirupati, India
K. V. S. Sarma
S. V. University, Tirupati, india
Abstract
The characteristics of Skiplot Sampling Plans (SkSP) originally developed by Dodge
and Perry are reconsidered in this paper from a computational point of view. The
reference plan plays an important role in the performance of SkSP. A Single Sampling
Plan (SSP) is normally used as reference plan and a number of procedures are
available to determine the SSP. We focus on the algorithm-based procedures instead
of methods based on statistical tables to determine the SSP and its effect on the
performance indicators of SkSP. Spreadsheet solutions are nowadays more user-
friendly than customized programs written in specific languages. We present a case of
using Excel worksheet functions to handle statistical distributions required in the
determination of the plan..The performance of SkSP is compared by generating a SSP
as reference plan using algorithms due to i) Guenther, ii) Modified Graf et a1. It is
shown that an admissible reference plan can always be generated with Excel functions
and templates are developed to obtain the characteristics of SkSP.
Keywords
SSP, MGM, Skiplot sampling plan, Excel, Solver
1. Introduction and Problem Environment
The Skiplot Sampling Plan (SkSP) as a variation in the Continuous Sampling Plan
(CSP) in which the inspection unit is a lot instead of an individual item. Under this
method each lot is 100% inspected in the order of arrival until i consecutive lots are
found free of defects. The method of inspection is then relaxed and a fraction f of
the incoming lots is only inspected (called sampling). This plan is called SkSP-l.
The idea is to reduce the effort of inspection when the quality history is found to be
Paper received in September 2006