Similar tasks, different effort : Why the same amount of functionality requires different development effort?

Since the appearance of Albrechts pioneering work, function points have attracted signi¿cant attention from the industry. In their work, project managers can benchmark function point counts obtained for their projects against large publicly available datasets such as the ISBSG development & enhancement repository release 11, containing function point counts for more than 5000 projects. Unfortunately, larger amount of functionality as re¿ected in the function points count does not necessarily correspond to a more signi¿cant development effort. In this paper we focus on a collection of ISBSG projects with a similar amount of functionality and study the impact of different project attributes on the development effort.