1、Designation: D6631 05 (Reapproved 2015)Standard Guide forCommittee D01 for Conducting an Interlaboratory Study forthe Purpose of Determining the Precision of a Test Method1This standard is issued under the fixed designation D6631; the number immediately following the designation indicates the year o
2、foriginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers a simplified statistical procedure forpl
3、anning and conducting interlaboratory evaluations of testmethods.2. Referenced Documents2.1 ASTM Standards:2E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine th
4、e Precision of a Test MethodE1345 Practice for Reducing the Effect of Variability ofColor Measurement by Use of Multiple Measurements3. Significance and Use3.1 The purpose of an interlaboratory evaluation, as definedin this guide, is to determine the variability of results obtainedin different labor
5、atories on equivalent equipment using aprescribed test method.3.2 The definitions of statistical terms used in this guide arecontained in Terminology E456.4. Problem Formulation4.1 The objective of the evaluation should be to clearlydefine the expected precision of the test method. Within thecurrent
6、 limits of both the software, and the statistical protocolscurrently available, this effectively restricts the use of thisguide to test methods which yield results that are continuous.This generally means a measured quantity, such as pH orbrightness. Results that are discrete (such as counts or pass
7、-fail), or ordered (ranked), present three special problems in thecreation of a meaningful precision statement:4.1.1 The amount of information contained in discrete andordered data is much less than in continuous data, necessitatingthe collection of much more data.4.1.2 The sensitivity (the ability
8、to discriminate betweensimilar samples) is much less in discrete and ordered data thancontinuous data.4.1.3 Since the precision statement relies on the normaldistribution, and the distributions of discrete and ordered dataare usually decidedly non-normal, the normal precision state-ment is invalid.4
9、.2 Given these concerns with discrete and ordered data, asimple statement of the results obtained in these types ofstudies might be the most useful information for a prospectiveuser of a test method.5. Preliminary5.1 Flow chart the test method.5.2 Survey known sources of information related to the t
10、estmethod to establish how results are affected by variations inoperating conditions, atmospheric conditions, differences be-tween operators, etc. Select what appears to be the optimumprocedure.5.3 Provide instructions for the test method and, withoutcomment, observe a laboratory technician perform
11、a testaccording to these instructions. Revise any parts of the draftcausing difficulty.5.4 If desirable, make a comparative study with other testmethods for measuring the property by using specimens with awide range of values of the property under test (and possiblywith wide ranges in other properti
12、es).6. Preparation for Interlaboratory Study6.1 Prepare a clear statement of the type of informationrequired from the interlaboratory evaluation.6.2 Based on the study made in one laboratory (Section 5),prepare a proposed master plan for the interlaboratory evalu-ation. Discuss the plan, in an open
13、meeting, if possible, withother participants in the study.1This guide is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.20 on Quality Assurance and Statistics.Current edition approved Dec. 1,
14、2015. Published December 2015. Originallyapproved in 2001. Last previous edition approved in 2011 as D6631 05 (2011).DOI: 10.1520/D6631-05R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards vol
15、ume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.3 Select the materials to be used in the interlaboratoryevaluations so as to:6.3.1 Cover the applicable
16、 range of the property or compo-nent to be measured, and6.3.2 Represent as many classes of materials as feasible, towhich the test method will be applied.7. Pilot Evaluation7.1 If the test method is new or the procedure for an old testmethod is greatly altered, a pilot study by one laboratoryinvolvi
17、ng a few materials (two or three) may reveal seriouslymisleading directions in the written procedure. A Box andWhisker Plot (as outlined in Practice E1345), or a Violin Plot3may help to clarify this evaluation.8. Participating Laboratory Qualification8.1 It is important that the managers of proposed
18、 partici-pants in an interlaboratory study be aware of the capability ofthose participants to run the method under study. This is not theresponsibility of the originator of the study, or ASTM. A Boxand Whisker Plot will also be helpful in this qualificationprotocol.9. First Interlaboratory Evaluatio
19、n9.1 For the first interlaboratory evaluation use at least threematerials to cover the expected range in property values andinclude all of the laboratories that will participate in the maininterlaboratory evaluation. This evaluation will clarify theprocedure, eliminate laboratories that do not compl
20、y with theprocedure because of nonstandard conditions or equipmentand, together with the main study, give some idea of-the timeconstancy of laboratory results.10. Main Interlaboratory Evaluation10.1 VariablesThe major variables that can be included inan interlaboratory evaluation of a test method ar
21、e: materials,laboratories, apparatus, and replicates, described as follows:(In the event that the minimums for these variables cannot bemet, it is advisable that the recommendation in 4.2 beconsidered, or that the study be abandoned).10.1.1 MaterialsA minimum of six materials differing inthe propert
22、y or component to be measured and covering theuseful scales of the process are needed to evaluate thesensitivity of a test method.10.1.2 LaboratoriesIn the evaluation of a test method, anabsolute minimum of three laboratories or locales must beused, but at least five are strongly recommended.10.1.3
23、ApparatusIf different types of apparatus (or differ-ent procedures) are to be included in the study, an absoluteminimum of three laboratories is required for each type. Atleast five are needed to obtain a reasonable estimate ofreproducibility. (It must be emphasized that the word “differ-ent” in thi
24、s section, could apply to multiple manufacturers, ormodels of equipment.) However, different equipment, usingdifferent techniques or protocols for measurement, forexample, rotational and efflux cup viscometers, must NOT beused in the same study.10.1.4 ReplicatesEach evaluation must at least be run i
25、nduplicate.10.2 Intralaboratory Precision is usually ascertained byhaving repeats made over the shortest possible time, preferablythe same day. If considered desirable, a completely unbiasedestimate of intralaboratory error can be obtained by use of“blind” repetition. In this procedure two samples o
26、f at leastone, and preferably more, of the test materials are distributed asseparate materials. If all the materials are duplicated, the totalamount of work can be kept the same by not repeating the testat another time. However, elimination of the time variablemight alert cooperators to the use of b
27、lind repetition which, inany event, is not readily applicable when all the test materialsdiffer markedly in properties.10.3 For analytical test methods, the precision of which isusually very good, two repeats each in duplicate are oftensufficient. However, owing to the much more variable nature ofme
28、asurements of the physical or application test properties, therepeats should be increased, unless it has been decided to usea test method mainly for ranking a series of materials. For mosttest methods of this type, three repeats should be used, but evenwhen the precision is quite poor the suggested
29、maximum isfour. If the intralaboratory variability is high, the number ofreplications should also be increased.10.4 In order to obtain sufficient interlaboratory degrees offreedom so that the estimated interlaboratory precision will notappear poorer than it really is, the number of laboratories must
30、increase as the number of test materials decreases.Materials Available Labs Needed544536NOTE 1In contrast to 10.1.1, regarding testing for sensitivity, thistable is designed to show the testing required to evaluate precision.10.5 Instructions to ParticipantUse the master planagreed upon by the evalu
31、ation group after careful discussion.This plan should include instructions on the following:10.5.1 Care of round-robin specimens and what to do incase of loss of specimens or results (missing results can beignored only if a sufficient number of participating laboratoriesand materials are included),1
32、0.5.2 Adjustment and calibration of the test apparatus,10.5.3 Order of testing the specimens,10.5.4 Recording results on the test form,10.5.5 Detailed test procedure, to include:10.5.5.1 Scope,10.5.5.2 Test method,10.5.5.3 Other instructions relevant to use of test method oroperation, as for example
33、, replication and standardization,10.5.5.4 Dates for performance of tests,10.5.5.5 Instructions about personnel,10.5.5.6 Instructions on compilation, calculation, andreporting,10.5.5.7 Standard report form for results and conditions,3Hintze, J. L., and Nelson, R. D., “Violin Plots: A Box Plot-Densit
34、y TraceSynergism,” The American Statistician, May 1998, pp. 181-184.D6631 05 (2015)210.5.5.8 Instructions on return of reports and, if applicable,materials (including address), and10.5.5.9 Closing date.10.6 Allocation of SpecimensIf appropriate, specimensmay be selected from several locales, but sho
35、uld be coordi-nated from one place. Prepare from each material enoughspecimens to provide the required test material for the partici-pating laboratories and a sufficient number of additionalspecimens for replacement of lost or spoiled specimens. Labeleach specimen by means of a code symbol and ident
36、ify thespecimens on a separate key sheet for future reference.Completely randomize the specimens of a particular materialbefore dividing them into groups to be distributed among thelaboratories. Where necessary, the same specimens may be sentin turn to each participating laboratory.10.7 Results Form
37、Supply each laboratory with resultsforms to ensure that all results and pertinent information arereported in a uniform manner. In addition to space formeasurement results, the form should provide space for suchinformation as: relative humidity, temperature, instrumenttype, deviations from the specif
38、ied procedure, unusualobservations, and constructive comments, as required.10.8 Final ReportAfter all participating laboratories re-port their results, and the results are analyzed statistically,according to Practice E691, or a method that yields equivalentresults, a research report shall be generat
39、ed giving suchinformation as: the raw data, the observations from 10.7, andthe statistical analysis results. In addition, a precision statement(and if appropriate, a bias statement), shall be created, accord-ing to Practice E177.11. Keywords11.1 bias; interlaboratory study; precisionASTM Internation
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43、 at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 05 (2015)3
