Software productivity metrics: who needs them?

Abstract

The measurement of productivity is seen variously as the key to successful software project estimation, to improvement of the efficiency and effectiveness of information system development and maintenance, and to demonstration of the performance of the information technology (IT) function within the business. The thesis of the paper is that measurement activities should focus on management purposes and should take into account the diverse concerns of managers at different levels. Even the term ‘productivity’ has varying interpretations, depending on management level, so that single measures used in isolation are inappropriate and can be counterproductive, especially in the realm of software development. At the project management level, productivity concerns are often centred on efficiency. For example, when estimating the effort needed to produce a system, assumptions must be made about the level of efficiency that will be achieved—ideally based on data from past projects. The paper identifies productivity measures appropriate for such situations, and the impact of each on the project management process. A higher-level view of software productivity is concerned with effectiveness: how much useful function is delivered to users by the applications delivery function? Here the focus is on the utility of delivered products, rather than on the amount of software which needs to be written to deliver the products. Management is concerned to establish an environment that maximizes output in terms of usable function. Hence the use of function points as a size measure derived from a user view of the system, and the use of function points per man-month as a productivity measure. However, to provide a more complete view of the effectiveness of the information system function, development effort alone is an insufficient representation of the input to the system: due account also needs to be taken of the costs of using the system, which could include equipment costs as well as user effort. Ultimately, businesses are concerned with the bottom-line contribution of IT. While lower-level measures of efficiency and effectiveness are important in achieving objectives at project and functional levels, higher-level views of the value of IT to the business, compared with the associated costs, are of concern to senior management. However, traditional return on investment and cost-benefit analyses have been found to be inadequate when applied to IT and difficult to relate to the lower-level measures of efficiency and effectiveness. Whatever the management level of concern, measuring productivity is, in itself, insufficient: the set of measurements used must address key performance indicators—anything else is waste, or pure history.