5.1 The POD analysis method described herein is based on well-known and well-established statistical methods. It shall be used to quantify the demonstrated POD for a specific set of examination parameters and known range of discontinuity sizes under the following conditions.

5.1.1 The initial response from a nondestructive evaluation inspection system is measurable and can be classified as a continuous variable.

5.1.2 The relationship between discontinuity size (a) and measured signal response (â) exists and is best described by a linear regression model with an error structure that is normally distributed with mean zero and constant variance, σ². (Note that "linear" refers to linear with respect to the model coefficients. For example, a quadratic model is a linear model.)

5.2 This practice does not limit the use of other statistical models if justified as more appropriate for the â versus a data.

5.3 This practice is not appropriate for data resulting from a POD examination on nondestructive evaluation systems that generate an initial response that is binary in nature (for example, hit/miss). Practice E2862 is appropriate for systems that generate a hit/miss-type response (for example, fluorescent penetrant).

5.4 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; the POD examination administration procedure (including data collection method) is well designed, well defined, under control, and unbiased; the initial inspection system response is measurable and continuous in nature; the inspection system is calibrated; and the measurement error has been evaluated and deemed acceptable. The analysis results are only valid if the â versus a data are accurate and precise and the linear model adequately represents the â versus a data.

5.5 The POD analysis method described herein is consistent with the analysis method for â versus a data described in MIL-HDBK-1823A and is included in several widely utilized POD software packages to perform a POD analysis on â versus a data. It is also found in statistical software packages that have linear regression capability. This practice requires that the analyst has access to either POD software or other software with linear regression capability.