The Effect of the Number of Defects on Estimates Produced by Capture-Recapture Models

Project managers use inspection data as input to capture-recapture (CR) models to estimate the total number of faults present in a software artifact. The CR models use the number of faults found during an inspection and the overlap of faults among inspectors to calculate the estimate. A common belief is that CR models underestimate the number of faults but their performance can be improved with more input data. This paper investigates the minimum number of faults that has to be present in an artifact before the CR method can be used. The result shows that the minimum number of faults varies from ten faults to twenty-three faults for different CR estimators.