For a given Eddy Current (EC) system, the relationship between the EC response and crack size can be evaluated by scanning a set of standard specimens with a known number and distribution of crack sizes. The results are analyzed using the Ii versus a analysis method to quantity the relationshipbetween the EC response (i.e., Ii) and crack size (i.e., a) and develop a Probability of Detection (POD) curve, which defines the crack size that can be detected with a specified level of reliability. This paper provides a practical overview of the Ii versus a methodology and illustrates how some of the analysis inputs impact an Ii versus a analysis.

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