Significance and Use
The POD analysis method described herein is based on a well-known and well established statistical method. It shall be used to quantify the demonstrated POD for a specific set of examination parameters and known range of discontinuity sizes when the initial response from a nondestructive evaluation inspection system is ultimately binary in nature (that is, hit or miss). This method requires that a relationship between discontinuity size and POD exists and is best described by a generalized linear model with the appropriate link function for binary outcomes.
Prior to performing the analysis it is assumed that the discontinuity of interest is clearly defined; the number and distribution of induced discontinuity sizes in the POD specimen set is known and well-documented; discontinuities in the POD specimen set are unobstructed; the POD examination administration procedure (including data collection method) is well-defined, under control, and unbiased; and the initial response is ultimately binary in nature (that is, hit or miss). The analysis results are only valid if convergence is achieved and the model adequately represents the data.
The POD analysis method described herein is consistent with the analysis method for binary data described in MIL-HDBK-1823A, which is included in several widely utilized POD software packages to perform a POD analysis on hit/miss data. It is also found in statistical software packages that have generalized linear modeling capability. This practice requires that the analyst has access to either POD software or other software with generalized linear modeling capability.
1.1 This practice defines the procedure for performing a statistical analysis on nondestructive testing hit/miss data to determine the demonstrated probability of detection (POD) for a specific set of examination parameters. Topics covered include the standard hit/miss POD curve formulation, validation techniques, and correct interpretation of results.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
hit/miss analysis; Probability of Detection; POD; POD analysis; penetrant POD;
ICS Number Code 03.120.30 (Application of statistical methods); 19.100 (Non-destructive testing)
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Citing ASTM Standards
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