The Added Value of Enhancement Function Points - An Empirical Evaluation

In 1998 NESMA published an alternative approach to establish the functional size of software enhancement projects. The aim of the approach was to be able to use productivity data from software development to estimate software enhancement. This approach has been highly debated, since it is not a pure functional size measurement method in the ISO/IEC 14143 definition. The approach is in use all over the world and is the most downloaded NESMA document. It is also the basis for many contracts where software enhancement has been outsourced. As far as we have been able to determine there is no public data available about the added value of the Enhancement Function Points approach over standard Function Point Analysis. Therefore we have conducted an empirical evaluation of the added value of this approach in a single environment. Based on this evaluation we do not see any added value of this approach over the standard method. Based on this evaluation there is reason to question the validity of the use of a single productivity figure for both software development and software enhancement.