Multi-Method Research: An Empirical Investigation of Object-Oriented Technology

There is a general acceptance that software engineering research should be supported by empirical evaluation. To make real progress researchers must address the difficulties caused by the human-intensive nature of software development as well as experimental validity. This paper proposes the use of multi-method empirical research programs, as an alternative to 'single-shot' empirical studies, to help address these problems. The multi-method approach is based on the combination of complementary empirical research methods. The intention is that the complementary nature of the research methods compensate for weaknesses inherent in individual methods. It is argued that the multi-method approach potentially provides benefits in terms of more robust conclusions, development and investigation of research hypotheses in an evolutionary manner, and increased understanding of research results. This paper demonstrates an application of the multi-method approach in an empirical investigation of object-oriented technology. This research program consists of a set of structured interviews with practitioners of object-oriented technology, followed by a wide-scale questionnaire survey, and concludes with a set of three controlled laboratory experiments which investigated one of the key findings from the exploratory interview and questionnaire phases. This application finds evidence that unconstrained inheritance usage in object-oriented software may inhibit software maintenance. The paper concludes that the multi-method approach offers the possibility of more reliable and generalizable results from empirical software engineering research.