ASTM E1994-09
(Practice)Standard Practice for Use of Process Oriented AOQL and LTPD Sampling Plans
Standard Practice for Use of Process Oriented AOQL and LTPD Sampling Plans
SIGNIFICANCE AND USE
Two general types of tables (Note 1) are given, one based on the concept of lot tolerance, LTPD, and the other on AOQL. The broad conditions under which the different types have been found best adapted are indicated below.
For each of the types, tables are provided both for single sampling and for double sampling. Each of the individual tables constitutes a collection of solutions to the problem of minimizing the over-all amount of inspection. Because each line in the tables covers a range of lot sizes, the AOQL values in the LTPD tables and the LTPD values in the AOQL tables are often conservative.
Note 1—Tables in Annex A1-Annex A4 and parts of the text are reproduced by permission of John R. Wiley and Sons. More extensive tables and discussion of the methods will be found in that text.
The sampling tables based on lot quality protection (LTPD) (the tables in Annex A1 and Annex A2) are perhaps best adapted to conditions where interest centers on each lot separately, for example, where the individual lot tends to retain its identity either from a shipment or a service standpoint. These tables have been found particularly useful in inspections made by the ultimate consumer or a purchasing agent for lots or shipments purchased more or less intermittently.
The sampling tables based on average quality protection (AOQL) (the tables in Annex A3 and Annex A4) are especially adapted for use where interest centers on the average quality of product after inspection rather than on the quality of each individual lot and where inspection is, therefore, intended to serve, if necessary, as a partial screen for defective pieces. The latter point of view has been found particularly helpful, for example, in consumer inspections of continuing purchases of large quantities of a product and in manufacturing process inspections of parts where the inspection lots tend to lose their identity by merger in a common storeroom from which quantities are withdrawn on order as needed.
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SCOPE
1.1 This practice is primarily a statement of principals for the guidance of ASTM technical committees and others in the use of Average Outgoing Quality Limit, AOQL, and Lot Tolerance Percent Defective, LTPD, sampling plans for determining acceptable of lots of product.
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Designation: E1994 − 09 AnAmerican National Standard
Standard Practice for
1
Use of Process Oriented AOQL and LTPD Sampling Plans
This standard is issued under the fixed designation E1994; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This standard is an abbreviated compilation of the sampling plans presented by H.F. Dodge and
H.G. Romig in their classic development of sampling plans for use with the process associated with
acontinuingsupplyofproducts.ThesocalledAOQLplansprovideameansfordispositionofproduct
whether or not the process is in control as well as incentives for process improvement in terms of
reduced sample size as the process average percent defective is lowered. In addition, so called LTPD
plans are provided for use with individual lots of product, not necessarily associated with a process
stream.
The sampling plans and parts of the text given here are taken from the Wiley Classics Library
Edition of the Dodge-Romig tables (copyright 1998).Additional tables and detailed discussion of the
2
plans, OC curves, and their derivation will be found in that text. The theoretical development of the
3,4
Dodge-Roming plans will be found in Volumes 8 and 20 of the Bell System Technical Journal and
5
an amplification of the plans is given in Acceptance Sampling in Quality Control.
1. Scope 3. Terminology
3.1 Definitions—Terminology E456 provides a more exten-
1.1 This practice is primarily a statement of principals for
sive list of terms in E11 standards.
the guidance of ASTM technical committees and others in the
use of Average Outgoing Quality Limit, AOQL, and Lot
3.2 average quality protection—a type of protection in
Tolerance Percent Defective, LTPD, sampling plans for deter-
whichthereisprescribedsomechosenvalueofaveragepercent
mining acceptable of lots of product.
defective in the product after inspection (average outgoing
quality limit (AOQL), that shall not be exceeded in the long
2. Referenced Documents run no matter what may be the level of percent defective in the
product submitted to the inspector.
6
2.1 ASTM Standards:
3.3 average outgoing quality (AOQ)—the average percent
E178 Practice for Dealing With Outlying Observations
defective of outgoing product including all accepted lots or
E456 Terminology Relating to Quality and Statistics
batches,afteranydefectiveunitsfoundinthemarereplacedby
acceptableunits,plusalllotsorbatcheswhicharenotaccepted
after such lots or batches have been effectively 100 % in-
1
This practice is under the jurisdiction ofASTM Committee E11 on Quality and
spected and all defective units replaced by acceptable units.
Statistics and is the direct responsibility of Subcommittee E11.30 on Statistical
Quality Control. 3.4 average outgoing quality limit (AOQL)—the maximum
Current edition approved Nov. 1, 2009. Published December 2009. Originally
of the AOQs for all possible incoming percentages defective
approved in 1998. Last previous edition approved in 2008 as E1994 – 08. DOI:
for the process, for a given acceptance sampling plan.
10.1520/E1994-09.
2
Available from John Wiley and Sons, Inc., 605 Third Ave., New York, NY
3.5 lot quality protection—a type of protection in which
10158.
there is prescribed some chosen value of limiting percent
3
Dodge, H. F. and Romig, H. G., “AMethod of Sampling Inspection,” The Bell
defective in a lot (lot tolerance percent defective, (LTPD)) and
System Technical Journal, Vol 8 , No. 10, 1924, pp. 613–631.
4
Dodge, H. F. and Romig, H. G., “Single Sampling and Double Sampling
also some chosen value for the probability (called the consum-
Inspection Tables,” The Bell System Technical Journal, Vol 20, No. 1, 1941, pp.
er’s risk) of accepting a submitted lot that has a percent
1–61.
defective equal to the lot tolerance percent defective.
5
Schilling, E. G., Acceptance Sampling in Quality Control, Marcel Dekker Inc.,
NY, 1982, pp. 372–399.
3.6 lot tolerance percent defective (LTPD)—for purposes of
6
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
acceptance sampling, the percentage of defective units in a lot
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
for which the consumer has a stated low probability of
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. acceptance of the lot.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E1994 − 09
3.7 Definitions of Terms Specific to This Standard: sampling. This
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This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
An American National Standard
Designation:E1994–08 Designation:E1994–09
Standard Practice for
1
Use of Process Oriented AOQL and LTPD Sampling Plans
This standard is issued under the fixed designation E1994; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This standard is an abbreviated compilation of the sampling plans presented by H.F. Dodge and
H.G. Romig in their classic development of sampling plans for use with the process associated with
acontinuingsupplyofproducts.ThesocalledAOQLplansprovideameansfordispositionofproduct
whether or not the process is in control as well as incentives for process improvement in terms of
reduced sample size as the process average percent defective is lowered. In addition, so called LTPD
plans are provided for use with individual lots of product, not necessarily associated with a process
stream.
The sampling plans and parts of the text given here are taken from the Wiley Classics Library
Edition of the Dodge-Romig tables (copyright 1998).Additional tables and detailed discussion of the
2
plans, OC curves, and their derivation will be found in that text. The theoretical development of the
,
3 4
Dodge-Roming plans will be found in Volumes 8 and 20 of the Bell System Technical Journal and
5
an amplification of the plans is given in Acceptance Sampling in Quality Control.
1. Scope
1.1 This practice is primarily a statement of principals for the guidance of ASTM technical committees and others in the use
of Average Outgoing Quality Limit, AOQL, and Lot Tolerance Percent Defective, LTPD, sampling plans for determining
acceptable of lots of product.
2. Referenced Documents
6
2.1 ASTM Standards:
E178 Practice for Dealing With Outlying Observations
E456 Terminology Relating to Quality and Statistics
3. Terminology
3.1 Definitions—Terminology E456 provides a more extensive list of terms in E11 standards.
3.2 lot tolerance percent defective (LTPD)—the percentage of defective units in a batch or lot for which, for purposes of
acceptance sampling, the consumer wishes the probability of acceptance to be restricted to a specified low value, specifically 10%
for this practice. This is also referred to by the more general term limiting quality taken at 10% consumer risk. average quality
protection—a type of protection in which there is prescribed some chosen value of average percent defective in the product after
inspection (average outgoing quality limit (AOQL), that shall not be exceeded in the long run no matter what may be the level
of percent defective in the product submitted to the inspector.
3.3 average outgoing quality (AOQ)—the average percent defective of outgoing product including all accepted lots or batches,
after any defective units found in them are replaced by acceptable units, plus all lots or batches which are not accepted after such
lots or batches have been effectively 100 % inspected and all defective units replaced by acceptable units.
1
This practice is under the jurisdiction ofASTM Committee E11 on Quality and Statistics and is the direct responsibility of Subcommittee E11.30 on Statistical Quality
Control.
Current edition approved Oct.Nov. 1, 2008.2009. Published October 2008.December 2009. Originally approved in 1998. Last previous edition approved in 20032008 as
E1994–98(2003).E1994 – 08. DOI: 10.1520/E1994-08.
2
Available from John Wiley and Sons, Inc., 605 Third Ave., New York, NY 10158.
3
Dodge, H. F. and Romig, H. G., “A Method of Sampling Inspection,” The Bell System Technical Journal, Vol 8 , No. 10, 1924, pp. 613–631.
4
Dodge, H. F. and Romig, H. G., “Single Sampling and Double Sampling Inspection Tables,” The Bell System Technical Journal, Vol 20, No. 1, 1941, pp. 1–61.
5
Schilling, E. G., Acceptance Sampling in Quality Control, Marcel Dekker Inc., NY, 1982, pp. 372–399.
6
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
E1994–09
3.4 average outgoing quality limit (AOQL)—the maximum of theAOQs for all
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