Qualitative and semi-quantitative modelling and simulation of the software engineering processes

Abstract

Software process modelling has been identified as being a vehicle for understanding development processes, controlling development costs, duration, and achieving product quality. In recent years, software process simulation has been becoming one of the essential techniques for effectively investigating and managing software development processes. Till now, most researches focus on the quantitative aspects of process simulation and modelling. Nevertheless, purely quantitative process modelling requires a very detailed understanding and accurate measurement of the software process, which relies on reliable and precise historical data. When such data are lacking or the quality is dubious, quantitative models have to impose severe constraints that restrict the model's value. Unfortunately, these data are not readily available in most cases, especially in the organisations at low process maturity levels. In addition, software development is a highly complex, human-centred endeavour, which involves many uncertain factors in the course of development process. Facing the inherent uncertainty and contingency, though quantitative modelling employs statistic techniques, its conditional capability and underlying assumptions limit its performance on large scale problems. As the alternatives of quantitative approaches, qualitative modelling can cope with a lack of complete knowledge, and predicts qualitative process behaviours. Furthermore, semi-quantitative modelling offers the capability of handling process uncertainty with limited knowledge, and achieves tradeoff between quantitative and qualitative approaches. However, most previous researches omitted these approaches, and the associated methods and applications are far from developed. The main contribution of this research lies in the pioneering work on the models, methods, and applications of qualitative and semi-quantitative software process modelling and simulation, and their relations with the conventional, quantitative modelling approaches. This dissertation produces its novelty from twofold research. Firstly, it explores methods and techniques to qualitatively and semi-quantitatively model and simulate software processes at different levels, i.e. project, portion of development process, and product evolution. Secondly, Some exclusive applications of these modelling approaches are also developed for aspects of software engineering practice. Moreover, a proposed framework integrates these approaches with typical quantitative paradigms to guide the adoption of process simulation modelling in software organisations. As a comprehensive reflection of state-of-the-art of software process simulation modelling, a systematic review is reported in this dissertation as well