Code inspections have been used on the 5ESS switch project since 1983. Beginning with a training program for all the developers involved in the project, code inspections have improved with each new 5ESS switch generic. Variations on a standard SQC (statistical quality control) technique, the control chart, have been used to track the metrics indicative of the effectiveness of code inspections. Parameters used in the computation of these metrics include the preparation effort, inspection time, number of inspectors, the size of the inspected unit of code, and the number of errors found at the inspection. It is noted that the exact form that these control charts have taken has evolved and improved with experience.>