A metric of calculating signal detection variables was devised using the ASTM A802 SCRATA plates. Levels B4, C1, and J1 were used.
The ASTM A802 SCRATA (Steel Castings Research and Trade Association) plates are a set of plastic plates measuring 3” x 5” created to simulate common surface textures of castings.
They were developed as a standard to be used for identifying surface features of castings using visual inspection. Level B4 represents surface inclusions, C1 represents gas porosity, and J1 represents welds.
So that signal detection theory could be used, each casting to be inspected by the participants was examined using the SCRATA plates as a reference, and the total number of anomalies on each part was recorded in addition to the location of each anomaly.