How Simple is It to Measure Software Size and Complexity for an IT Practitioner?

An empirical study was conducted in order to evaluate the simplicity of FPA, COSMIC and Paths, from the IT practitioners\´ viewpoint. The results have shown that P are the simplest measure because they presented a significantly lower measurement time. The study has also been useful to see which aspects of Paths should be clarified in order to facilitate the practitioners\´ application of this measure and to demonstrate in a mathematical form how the complexity of an application which is measured with P increases if the number of "transactions" increases. The results obtained cannot be generalized because the number of measurements performed was small, and the subjects had particular characteristics, but a new empirical study using use case textual descriptions of different domains and subjects with different characteristics is expected to solve this limitation.