Common Factors Influencing Software Project Effort

The effort required for developing software depends on a number of factors. The major determinant of development effort is the “size” of software, typically approximated in terms of the amount of functionality delivered by the software or the structural size of artifacts delivered by software engineering processes. Still, developing software of comparable size may require significantly different amounts of effort. This variance is related to differences in development productivity, which in turn depends on the environment of the software development project. The ability to reliably estimate software size, knowledge of the most relevant factors influencing development productivity, and an understanding of how they influence productivity are the three pillars of successful prediction of software development effort. The topic of measuring software size is so extensive that it deserves its own book (at least one) and thus is beyond the scope of this work; in Appendix A, we briefly present the most common ways of measuring software size with their most prominent strengths and weaknesses. In this chapter, we discuss common factors that determine software development productivity and thus should be considered when estimating software project effort.