Abstract
The goal of this paper is to investigate and assess the ability of explanatory models based on design metrics to describe and predict defect counts in an object-oriented software system. Specifically, the paper empirically evaluates the influence of design decisions to defect behavior of the classes in two products from the commercial software domain. Information provided by these models can help in resource allocation and serve as a base for assessment and future improvements. The paper forms a framework for comparison of models' descriptive and predictive ability. Predictive capability of the models to identify most critical classes in the system early in the software development process can help in allocation of resources and foster software quality improvement.