Reference Values for Object-Oriented Software Metrics

Although a large quantity of OO software has been produced, little is known about the actual structure of this type of software. There is a large number of proposed metrics for OO software, but they are still not employed effectively in industry. A reason for this is that there are few data published about this topic, and typical values of the metrics are not known. This paper presents the results of a study carried out on a large collection of open-source software developed in Java. The objective of this study was to identify characteristics of this type of software in terms of a set of metrics for OO software, such as connectivity, class cohesion and depth of a class in its inheritance tree. The results of the study provide important insights on the structure of open-source OO software and exhibit values that can be taken as baselines for the values of measures of the metrics.