ASTM D6299-2008 752 Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance.pdf

1、Designation: D 6299 08An American National StandardStandard Practice forApplying Statistical Quality Assurance and Control ChartingTechniques to Evaluate Analytical Measurement SystemPerformance1This standard is issued under the fixed designation D 6299; the number immediately following the designat

2、ion indicates the year oforiginal 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 practice covers information f

3、or the design andoperation of a program to monitor and control ongoing stabilityand precision and bias performance of selected analyticalmeasurement systems using a collection of generally acceptedstatistical quality control (SQC) procedures and tools.NOTE 1A complete list of criteria for selecting

4、measurement systemsto which this practice should be applied and for determining the frequencyat which it should be applied is beyond the scope of this practice.However, some factors to be considered include (1) frequency of use ofthe analytical measurement system, (2) criticality of the parameter be

5、ingmeasured, (3) system stability and precision performance based onhistorical data, (4) business economics, and (5) regulatory, contractual, ortest method requirements.1.2 This practice is applicable to stable analytical measure-ment systems that produce results on a continuous numericalscale.1.3 T

6、his practice is applicable to laboratory test methods.1.4 This practice is applicable to validated process streamanalyzers.1.5 This practice is applicable to monitoring the differencesbetween two analytical measurement systems that purport tomeasure the same property provided that both systems haveb

7、een assessed in accordance with the statistical methodology inPractice D 6708 and the appropriate bias applied.NOTE 2For validation of univariate process stream analyzers, see alsoPractice D 3764.NOTE 3One or both of the analytical systems in 1.5 can be laboratorytest methods or validated process st

8、ream analyzers.1.6 This practice assumes that the normal (Gaussian) modelis adequate for the description and prediction of measurementsystem behavior when it is in a state of statistical control.NOTE 4For non-Gaussian processes, transformations of test resultsmay permit proper application of these t

9、ools. Consult a statistician forfurther guidance and information.2. Referenced Documents2.1 ASTM Standards:2D 3764 Practice for Validation of the Performance of Pro-cess Stream Analyzer SystemsD 5191 Test Method for Vapor Pressure of Petroleum Prod-ucts (Mini Method)D 6708 Practice for Statistical A

10、ssessment and Improve-ment of Expected Agreement Between Two Test Methodsthat Purport to Measure the Same Property of a MaterialD 6792 Practice for Quality System in Petroleum Productsand Lubricants Testing LaboratoriesD 7372 Guide forAnalysis and Interpretation of ProficiencyTest Program ResultsE 1

11、77 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 178 Practice for Dealing With Outlying ObservationsE 456 Terminology Relating to Quality and StatisticsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitio

12、ns:3.1.1 accepted reference value, na value that serves as anagreed-upon reference for comparison and that is derived as (1)a theoretical or established value, based on scientific principles,(2) an assigned value, based on experimental work of somenational or international organization, such as the

13、U.S. Na-tional Institute of Standards and Technology (NIST), or (3)aconsensus value, based on collaborative experimental workunder the auspices of a scientific or engineering group.E 177, E 4563.1.2 accuracy, nthe closeness of agreement between anobserved value and an accepted reference value. E 177

14、,E 4563.1.3 assignable cause, na factor that contributes tovariation and that is feasible to detect and identify. E 4561This practice is under the jurisdiction of ASTM Committee D02 on PetroleumProducts and Lubricants and is the direct responsibility of Subcommittee D02.94 onCoordinating Subcommitte

15、e on Quality Assurance and Statistics.Current edition approved Oct. 15, 2008. Published November 2008. Originallyapproved in 1998. Last previous edition approved in 2007 as D 6299071.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.

16、org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.4 bias, na systematic error that contributes to thedifferen

17、ce between a population mean of the measurements ortest results and an accepted reference or true value. E 177,E 4563.1.5 control limits, nlimits on a control chart that areused as criteria for signaling the need for action or for judgingwhether a set of data does or does not indicate a state ofstat

18、istical control. E 4563.1.6 lot, na definite quantity of a product or materialaccumulated under conditions that are considered uniform forsampling purposes. E 4563.1.7 precision, nthe closeness of agreement between testresults obtained under prescribed conditions. E 4563.1.8 repeatability conditions

19、, nconditions where mutu-ally independent test results are obtained with the same testmethod in the same laboratory by the same operator with thesame equipment within short intervals of time, using testspecimens taken at random from a single sample of material.E 177, E 4563.1.9 reproducibility condi

20、tions, nconditions under whichtest results are obtained in different laboratories with the sametest method, using test specimens taken at random from thesame sample of material. E 177, E 4563.2 Definitions of Terms Specific to This Standard:3.2.1 analytical measurement system, na collection of oneor

21、 more components or subsystems, such as samplers, testequipment, instrumentation, display devices, data handlers,printouts or output transmitters, that is used to determine aquantitative value of a specific property for an unknownsample in accordance with a test method.3.2.1.1 DiscussionA standard t

22、est method (for example,ASTM, ISO) is an example of an analytical measurementsystem.3.2.1.2 DiscussionAn analytical measurement systemmay comprise multiple instruments being used for the sametest method provided there is no statistically observable biasand precision differences between the multiple

23、instruments.3.2.2 blind submission, nsubmission of a check standardor quality control (QC) sample for analysis without revealingthe expected value to the person performing the analysis.3.2.3 check standard, nin QC testing, a material havingan accepted reference value used to determine the accuracy o

24、fa measurement system.3.2.3.1 DiscussionA check standard is preferably a mate-rial that is either a certified reference material with traceabilityto a nationally recognized body or a material that has anaccepted reference value established through interlaboratorytesting. For some measurement systems

25、, a pure, single com-ponent material having known value or a simple gravimetric orvolumetric mixture of pure components having calculablevalue may serve as a check standard. Users should be awarethat for measurement systems that show matrix dependencies,accuracy determined from pure compounds or sim

26、ple mixturesmay not be representative of that achieved on actual samples.3.2.4 common (chance, random) cause, nfor quality as-surance programs, one of generally numerous factors, individu-ally of relatively small importance, that contributes to varia-tion, and that is not feasible to detect and iden

27、tify.3.2.5 double blind submission, nsubmission of a checkstandard or QC sample for analysis without revealing the checkstandard or QC sample status and expected value to the personperforming the analysis.3.2.6 in-statistical-control, adja process, analytical mea-surement system, or function that ex

28、hibits variations that canonly be attributable to common cause.3.2.7 proficiency testing, ndetermination of a laboratorystesting capability by participation in an interlaboratory cross-check program.3.2.7.1 DiscussionASTM Committee D02 conducts pro-ficiency testing among hundreds of laboratories, us

29、ing a widevariety of petroleum products and lubricants.3.2.8 quality control (QC) sample, nfor use in qualityassurance programs to determine and monitor the precision andstability of a measurement system, a stable and homogeneousmaterial having physical or chemical properties, or both,similar to tho

30、se of typical samples tested by the analyticalmeasurement system. The material is properly stored to ensuresample integrity, and is available in sufficient quantity forrepeated, long term testing.3.2.9 site expected value (SEV), nfor a QC sample this isan estimate of the theoretical limiting value t

31、owards which theaverage of results collected from a single in-statistical-controlmeasurement system under site precision conditions tends asthe number of results approaches infinity.3.2.9.1 DiscussionThe SEV is associated with a singlemeasurement system; for control charts that are plotted inactual

32、measured units, the SEV is required, since it is used asa reference value from which upper and lower control limits forthe control chart specific to a batch of QC material areconstructed.3.2.10 site precision (R8), nthe value below which theabsolute difference between two individual test results obt

33、ainedunder site precision conditions may be expected to occur witha probability of approximately 0.95 (95 %). It is defined as 2.77times the standard deviation of results obtained under siteprecision conditions.3.2.11 site precision conditions, nconditions under whichtest results are obtained by one

34、 or more operators in a singlesite location practicing the same test method on a singlemeasurement system which may comprise multiple instru-ments, using test specimens taken at random from the samesample of material, over an extended period of time spanningat least a 15 day interval.3.2.11.1 Discus

35、sionSite precision conditions should in-clude all sources of variation that are typically encounteredduring normal, long term operation of the measurement sys-tem. Thus, all operators who are involved in the routine use ofthe measurement system should contribute results to the siteprecision determin

36、ation. If multiple results are obtained withina 24h period, then it is recommended that the number ofresults used in site precision calculations be increased tocapture the longer term variation in the system.3.2.12 site precision standard deviation, nthe standarddeviation of results obtained under s

37、ite precision conditions.D62990823.2.13 validation audit sample, na QC sample or checkstandard used to verify precision and bias estimated fromroutine quality assurance testing.3.3 Symbols:3.3.1 ARVaccepted reference value.3.3.2 EWMAexponentially weighted moving average.3.3.3 Iindividual observation

38、 (as in I-chart).3.3.4 MRmoving range.MR average of moving range.3.3.6 QCquality control.3.3.7 R8site precision.3.3.8 SEVsite expected value.3.3.9 sR8site precision standard deviation.3.3.10 VAvalidation audit.3.3.11 x2chi squared.3.3.12 llambda.4. Summary of Practice4.1 QC samples and check standar

39、ds are regularly analyzedby the measurement system. Control charts and other statisticaltechniques are presented to screen, plot, and interpret testresults in accordance with industry-accepted practices to as-certain the in-statistical-control status of the measurementsystem.4.2 Statistical estimate

40、s of the measurement system preci-sion and bias are calculated and periodically updated usingaccrued data.4.3 In addition, as part of a separate validation auditprocedure, QC samples and check standards may be submittedblind or double-blind and randomly to the measurement systemfor routine testing t

41、o verify that the calculated precision andbias are representative of routine measurement system perfor-mance when there is no prior knowledge of the expected valueor sample status.5. Significance and Use5.1 This practice can be used to continuously demonstratethe proficiency of analytical measuremen

42、t systems that areused for establishing and ensuring the quality of petroleum andpetroleum products.5.2 Data accrued, using the techniques included in thispractice, provide the ability to monitor analytical measurementsystem precision and bias.5.3 These data are useful for updating test methods as w

43、ellas for indicating areas of potential measurement system im-provement.6. Reference Materials6.1 QC samples are used to establish and monitor theprecision of the analytical measurement system.6.1.1 Select a stable and homogeneous material havingphysical or chemical properties, or both, similar to t

44、hose oftypical samples tested by the analytical measurement system.NOTE 5When the QC sample is to be utilized for monitoring aprocess stream analyzer performance, it is often helpful to supplement theprocess analyzer system with a subsystem to automate the extraction,mixing, storage, and delivery fu

45、nctions associated with the QC sample.6.1.2 Estimate the quantity of the material needed for eachspecific lot of QC sample to (1) accommodate the number ofanalytical measurement systems for which it is to be used(laboratory test apparatuses as well as process stream analyzersystems) and (2) provide

46、determination of QC statistics for auseful and desirable period of time.6.1.3 Collect the material into a single container and isolateit.6.1.4 Thoroughly mix the material to ensure homogeneity.6.1.5 Conduct any testing necessary to ensure that the QCsample meets the characteristics for its intended

47、use.6.1.6 Package or store QC samples, or both, as appropriatefor the specific analytical measurement system to ensure thatall analyses of samples from a given lot are performed onessentially identical material. If necessary, split the bulkmaterial collected in 6.1.3 into separate and smaller contai

48、nersto help ensure integrity over time. (WarningTreat thematerial appropriately to ensure its stability, integrity, andhomogeneity over the time period for which it is to stored andused. For samples that are volatile, such as gasoline, storage inone large container that is repeatedly opened and clos

49、ed canresult in loss of light ends. This problem can be avoided bychilling and splitting the bulk sample into smaller containers,each with a quantity sufficient to conduct the analysis. Simi-larly, samples prone to oxidation can benefit from splitting thebulk sample into smaller containers that can be blanketed withan inert gas prior to being sealed and leaving them sealed untilthe sample is needed.)6.2 Check standards are used to estimate the accuracy of theanalytical measurement system.6.2.1 A check standard may be a commercial standa