ABSTRACT
Defect detection is one of the main objectives of nondestructive evaluation. This chapter looks at the different types of problems that can arise as a result of inspection and how these are defined and classified. Signals from defects exhibit a statistical distribution and therefore, in practice, not all defects will be detected. Furthermore, inspections can also suggest the presence of flaws where there are none. This latter condition is known as a
false alarm
. This chapter discusses both the probability of detection and the probability of false alarms and how the choice of accept-reject criteria can affect these probabilities.
