An empirical comparison and characterization of high defect and high complexity modules

We analyzed a large set of complexity metrics and defect data collected from six large-scale software products, two from IBM and four from Nortel Networks, to compare and characterize the similarities and differences between the high defect (HD) and high complexity modules. We observed that the most complex modules often have an acceptable quality and HD modules are not typically thc most complex ones. This observation was statistically validated through hypothesis testing. Our analyses also indicated that the clusters of modules with the highest defects are usually those whose complexity rankings are slightly below the most complex ones. These results should help us better understand the complexity behavior of HD modules and guide future software development and research efforts.