Empirical assessment of the impact of structural properties on the changeability of object-oriented software

The changeability of software can be viewed as the quality of being capable of change, which among others implies that the task of changing the software requires little effort. It is hypothesized that structural properties of the software affect changeability, in which case measures of such properties can be used as changeability indicators.Ways in which structural properties of the software can be measured are described and empirically validated based on data collected from an industrial Java development project. The measures are validated by using them as candidate variables in a multivariate regression model of the actual effort required to make modifications to the evolving software system.The results suggest that some measures that combine existing structural attribute measures with a weighting factor based on the relative proportion of change in each class can explain a large amount of the variation in change effort. This constitutes initial, empirical evidence that the proposed measures are valid changeability indicators. Consequently, they may help designers to identify and correct design problems during the development and maintenance of object-oriented software.