ASTM_E_2262_-_03_2014.pdf

Designation:E226203(Reapproved 2014)Standard Practice forEstimating Thurstonian Discriminal Distances1This standard is issued under the fixed designation E2262;the number immediately following the designation 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 describes procedures to estimate Thursto-nian discriminal distances(that is,d values)from dataobtained on two samples.Procedures are presented for fourforced-choice methods(that is,the triangle,the duo-trio,the3-alternative-forced-choice(or 3-AFC)and the 2-AFC(alsocalled the directional difference test),theA/Not-Amethod,theSame-Different method and for data obtained from orderedcategory scales.Procedures for estimating the variance of dare also presented.Thus,confidence intervals and statisticaltests can be calculated for d.1.2 The procedures in this document pertain only to theunidimensional,equal-variance model.Other,more compli-cated Thurstonian models,involving multiple dimensions andunequal variances exist but are not addressed in this standard.The procedure for forced-choice methods is limited to dichoto-mous responses.The procedure for the A/Not-A methodassumes equal sample sizes for the two samples.The procedurefor the Same-Different method assumes equal sample sizes forthe matched and unmatched pairs of samples.For all methods,only unreplicated tests are considered.(Tests in which eachassessor performs multiple(that is,replicated)evaluationsrequire different analyses.)1.3 Thurstonian scaling is a method for measuring theperceptual difference between two samples based on a proba-bilistic model for categorical choice decision making.Themagnitude of the perceived difference,can be estimatedfrom the assessors categorical choices using the methodsdescribed in this practice(See Appendix X3 for a more detaileddescription of Thurstonian scaling).1.4 In theory,the Thurstonian does not depend on themethod used to measure the difference between two samples.As such,provides a common scale of measure for comparingsamples measured under a variety of test conditions.Forexample,Thurstonian scaling can be used to compare productsmeasured under different test conditions,to compare panels(trained,consumer or both)that have evaluated the samesamples(using the same or different test methods)and tocompare test methods on their ability to discriminate samplesthat exhibit a fixed sensory difference.1.5 This standard may involve hazardous materials,opera-tions and equipment.This standard does not purport to addressall of the safety concerns,if any,associated with its use.It isthe responsibility of the user of this standard to establishappropriate safety and health practices and determine theapplicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E253 Terminology Relating to Sensory Evaluation of Mate-rials and ProductsE456 Terminology Relating to Quality and StatisticsE460 Practice for Determining Effect of Packaging on Foodand Beverage Products During StorageE679 Practice for Determination of Odor and Taste Thresh-olds By a Forced-Choice Ascending Concentration SeriesMethod of LimitsE1432 Practice for Defining and Calculating Individual andGroup Sensory Thresholds from Forced-Choice Data Setsof Intermediate SizeE1593 Guide forAssessing the Efficacy ofAir Care Productsin Reducing the Perception of Indoor MalodorE1627 Practice for Sensory Evaluation of Edible Oils andFatsE1697 Test Method for Unipolar Magnitude Estimation ofSensory AttributesE1810 Practice for Evaluating Effects of Contaminants onOdor and Taste of Exposed FishE1879 Guide for Sensory Evaluation of Beverages Contain-ing AlcoholE1885 Test Method for Sensory AnalysisTriangle TestE1958 Guide for Sensory Claim SubstantiationE2049 Guide for Quantitative Attribute Evaluation ofFragrance/Odors for Shampoos and Hair Conditioners byTrained Assessors1This practice is under the jurisdiction of ASTM Committee E18 on SensoryEvaluation and is the direct responsibility of Subcommittee E18.03 on SensoryTheory and Statistics.Current edition approved Sept.1,2014.Published September 2014.Originallyapproved in 2003.Last previous edition approved in 2009 as E2262 03(2009).DOI:10.1520/E2262-03R14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume 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 States1 E2164 Test Method for Directional Difference Test2.2 ASTM Publication:Manual 26 Sensory Testing Methods,2nd Edition22.3 ISO Standard:ISO 5495 Sensory AnalysisMethodologyPaired Com-parison33.Terminology3.1 For definitions of terms relating to se