‘Function point counting’, i.e. the process of measuring functional size of software, has claimed to be difficult and time consuming. Several experiments, including the ones organized by FiSMA and introduced below, have proven that the claim is not true, if the measurer knows his method, has fair tools and well-documented information available. Regrettably often system documentation (Product Requirements Document) is fuzzy and incomplete so that finding the functionality there is almost impossible, or at least extremely laborious. In the cases below we had organized the experiment so that the documentation was fairly well done and made it easy to find all the software functions required for counting. This was the way to recognize the true speed of size measurement process, without any disturbance from external sources, like exploring through poor documentation or explaining the details of measurement method to software developers and users.
23 Finnish software experts were invited to FiSMA office in Espoo in November 2015. The purpose of the meeting was to try, how fast they can measure functional size of software, if the circumstances are as good as they can. They were given the information of five systems or pieces of software in terms of numbers of different kind of functional components. For comparison, a similar type of experiment was arranged also 18 months earlier for a larger group of members of the FiSMA Scope Manager Forum. In that case they had measured software size using a professional tool, Experience® Service. The old “world record” from that case was measuring five applications with average speed of 2.7 minutes per software. The average measurement error of 60 measurers was only 1 % compared to the correct result. There they also completed effort estimation in a few extra minutes, still with astonishing success rate. This experiment has documented and published in a paper of MetriKon conference.
In the new ‘world record trial’ our experts concentrated only in software size measurement, using the freeware FiSMA function point calculator instead of professional Experience® Service. They measured the same applications in half a minute per application. Though the tool is simplified, the measurement errors didn’t exceed six percentages. Counting function points is really fast, if you have the information available, system architecture and amount of functional components of the system. In a well-managed software project all this information should be available with ease.