It is shown that the hyper-geometric distribution model can be applied to different types of test-and-debug data to estimate the number of initial software faults. Examples show that the fitness of the estimated growth curves of the model to real data is satisfactory. The relationship of the model to those proposed earlier is clarified. Some of them can be expressed as a special case of the proposed model. The S-shaped characteristic of the growth curve can also be introduced using this model.>

Models based on the hyper-geometric distribution for estimating the number of residual software faults are proposed. The application of the basic model shows that its fit to real data is good. Two ways of improving the model, using a segmentation technique and composite estimation, respectively, are shown. The segmentation technique appears quite effective, particularly when the growth curve of the cumulative number of detected faults bends sharply. The applications of these models to real data are demonstrated.>