Chapter 3 supplement, acceptance sampling. This chapter includes contents: Single-sample attribute plan, operating characteristic curve, developing a sampling plan with excel, average outgoing quality, double - and multiple-sampling plans.
OPERATIONS MANAGEMENT: Creating Value Along the Supply Chain, Canadian Edition Robert S Russell, Bernard W Taylor III, Ignacio Castillo, Navneet Vidyarthi CHAPTER SUPPLEMENT Acceptance Sampling Supplement 3-1 Lecture Outline Single-Sample Attribute Plan Operating Characteristic Curve Developing a Sampling Plan with Excel Average Outgoing Quality Double - and Multiple-Sampling Plans Supplement 3-2 Acceptance Sampling Accepting or rejecting a production lot based on the number of defects in a sample Not consistent with TQM or Zero Defects philosophy producer and customer agree on the number of acceptable defects a means of identifying not preventing poor quality percent of defective parts versus PPM Sampling plan provides guidelines for accepting a lot Supplement 3-3 Single–Sample Attribute Plan • Single sampling plan • • • • • N = lot size n = sample size (random) c = acceptance number d = number of defective items in sample If d ≤c, accept lot; else reject Supplement 3-4 Producer’s and Consumer’s Risk AQL or acceptable quality level proportion of defects consumer will accept in given lot or producer’s risk probability of rejecting a good lot LTPD or lot tolerance percent defective limit on the number of defectives the customer will accept β or consumer’s risk probability of accepting a bad lot Supplement 3-5 Producer’s and Consumer’s Risk Good Lot Reject No Error Type I Error Producer’ Risk Bad Lot Accept Type II Error Consumer’s Risk No Error Sampling Errors Supplement 3-6 Operating Characteristic (OC) Curve Shows probability of accepting lots of different quality levels with a specific sampling plan Assists management to discriminate between good and bad lots Exact shape and location of the curve is defined by the sample size (n) and acceptance level (c) for the sampling plan Supplement 3-7 OC Curve Supplement 3-8 Developing a Sampling Plan with OM Tools ABC Company produces mugs in lots of 10,000 Quality contracts require producer’s risk of 0.05 with an AQL of 1% defective and a consumer’s risk of 0.10 with a LTPD of 5% defective What size sample and what acceptance number should ABC use to achieve performance measures called for in the sampling plan? N = 10,000 α = 0.05 β = 0.10 AQL = 1% LTPD = 5% n=? C=? Supplement 3-9 Average Outgoing Quality (AOQ) Expected number of defective items that will pass on to customer with a sampling plan Average outgoing quality limit (AOQL) maximum point on the curve worst level of outgoing quality Supplement 3-10 AOQ Curve Supplement 3-11 Double-Sampling Plans Take small initial sample If # defective ≤ lower limit, accept If # defective > upper limit, reject If # defective between limits, take second sample Accept or reject based on samples Less costly than single-sampling plans Supplement 3-12 Multiple-Sampling Plans Uses smaller sample sizes Take initial sample If # defective ≤ lower limit, accept If # defective > upper limit, reject If # defective between limits, resample Continue sampling until accept or reject lot based on all sample data Supplement 3-13 COPYRIGHT Copyright © 2014 John Wiley & Sons Canada, Ltd All rights reserved Reproduction or translation of this work beyond that permitted by Access Copyright (The Canadian Copyright Licensing Agency) is unlawful Requests for further information should be addressed to the Permissions Department, John Wiley & Sons Canada, Ltd The purchaser may make back-up copies for his or her own use only and not for distribution or resale The author and the publisher assume no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information contained herein ... for distribution or resale The author and the publisher assume no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information contained... lots Exact shape and location of the curve is defined by the sample size (n) and acceptance level (c) for the sampling plan Supplement 3-7 OC Curve Supplement 3-8 Developing a Sampling Plan with... Average outgoing quality limit (AOQL) maximum point on the curve worst level of outgoing quality Supplement 3-1 0 AOQ Curve Supplement 3-1 1 Double-Sampling Plans Take small initial sample If #