ASTM_E_2862_-_12.pdf

Designation:E286212Standard Practice forProbability of Detection Analysis for Hit/Miss Data1This standard is issued under the fixed designation E2862;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 defines the procedure for performing astatistical analysis on nondestructive testing hit/miss data todetermine the demonstrated probability of detection(POD)fora specific set of examination parameters.Topics coveredinclude the standard hit/miss POD curve formulation,valida-tion techniques,and correct interpretation of results.1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E1316 Terminology for Nondestructive Examinations2.2 Department of Defense Handbook:MIL-HDBK-1823A Nondestructive Evaluation System Re-liability Assessment33.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 analyst,nthe person responsible for performing aPOD analysis on hit/miss data resulting from a POD examina-tion.3.1.2 demonstrated probability of detection,nthe calcu-lated POD value resulting from the statistical analysis on thehit miss data.3.1.3 false call,nthe perceived detection of a discontinu-ity that is identified as a find during a POD examination whenno discontinuity actually exists at the inspection site.3.1.4 hit,nan existing discontinuity that is identified as afind during a POD demonstration examination.3.1.5 miss,nan existing discontinuity that is missed dur-ing a POD examination.3.1.6 probability of detection,nthe fraction of nominaldiscontinuity sizes expected to be found given their existence.3.2 Symbols:3.2.1 adiscontinuity size.3.2.2 apthe discontinuity size that can be detected withprobability p.3.2.2.1 DiscussionEach discontinuity size has an indepen-dent probability of being detected and corresponding probabil-ity of being missed.For example,being able to detect a specificdiscontinuity size with probability p does not guarantee that alarger size discontinuity will be found.3.2.3 ap/cthe discontinuity size that can be detected withprobability p with a statistical confidence level of c.3.2.3.1 Discussionap/cis calculated by applying a statis-tical uncertainty bound to ap.The uncertainty bound is afunction the amount of data,the scatter in the data,and thespecified level of statistical confidence.The resulting valuerepresents how large the discontinuity with POD equal to pcould be when uncertainty associated with estimating apisaccounted for.Hence ap/c ap.Note that POD is equal to p forboth ap/cand ap.apis based solely on the hit/miss data resultingfrom the examination and represents a snapshot in time,whereas ap/caccounts for the uncertainty associated withlimited sample data.4.Summary of Practice4.1 This practice describes step-by-step the process foranalyzing nondestructive testing hit/miss data resulting from aPOD examination,including minimum requirements for vali-dating the resulting POD curve.4.2 This practice also includes definitions and discussionsfor results of interest(for example,a90/95)to provide forcorrect interpretation of results.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.10 onSpecialized NDT Methods.Current edition approved Jan.15,2012.Published February 2012.DOI:10.1520/E2862-12.2For 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.3Available from Standardization Documents Order Desk,DODSSP,Bldg.4,SectionD,700RobbinsAve.,Philadelphia,PA19111-5098,http:/dodssp.daps.dla.mil.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.Significance and Use5.1 The POD analysis method described herein is based ona well-known and well established statistical method.It shallbe used to quantify the demonstrated POD for a specific set ofexamination parameters and known range of discontinuitysizes when the initial response from a nondestructive evalua-tion inspection system is ultimately binary in nature(that is,hitor miss).This method requires that a relationship betweendiscontinuity size and POD exists and is best described