A control model of the software requirements process

Purpose - Many project failures can be attributed to changes in requirements as the project progresses. The purpose of this paper is to review several system dynamics models of the requirements process from the literature, especially the model of Andersson and Karlsson. This model addresses the deficiencies in the system dynamics model devised hitherto to create a model than can be used to predict requirements acquisition and staff resources for different levels of project complexity and size. Design/methodology/approach - A new control-theoretic model of requirements gathering is devised using the Software Test Model of Cangussu as a framework. Conventional control system techniques are then used to compute typical responses. Findings - The results agree with the limited published data. This model can be used to predict an estimate of the possible number of requirements that could be devised for the project. It allows the incorporation of workforce, quality and complexity information to predict the time to complete the requirements process. This model is then used to predict how the requirements process responds to requirements creep and to changes in workforce used. Research limitations/implications - This model is theoretical and is proposed so that it can be simple tested. It makes a number of assumptions not yet recorded by industry that would have to be obtained. Practical implications - If it is supported by experimental data then a better project development model can be created with the prospect of greater control of project development. Originality/value - This work, although based on the work of Cangussu et at, is devised by the author.