Analysis of Reliability and Effectiveness of Repeated Inspections Based on Correlated Probability of Detection

Repeated inspections have been reported to improve the reliability of nondestructive inspection and can be evaluated by multiplying the likelihood function. However, repeated inspections conducted by a single inspector may not be independent, because the subsequent inspections may be influenced by previous inspection results. The probability of detection (POD) quantifies the sensitivity and reliability of an inspection system. In this study, eddy-current inspection data were used to assess the effect of repeated inspections on POD improvement. Specifically, repeated measures correlation (RMC) analysis was performed, which did not violate the assumption of independence to analyze intra-individual association, considering the nonindependence of repeated measures. Nonindependent repeated inspections performed using a combination of two datasets reduced the uncertainty in POD. Moreover, RMC yielded further improvements in POD and reduced the uncertainty.