A Light Functional Dimension Estimation Model for Software Maintenance

Banca d´Italia has been one of the early adopters of function points analysis (FPA) as far as Italian panorama is concerned. Moreover Banca d´Italia has been a co-founder of Gruppo Utenti Fuction Points Italia (GUFPI-ISMA). For around ten years, Banca d´Italia has been using FPA to measure functional size of software especially in business relationship with suppliers. For six years, a dedicated organizational unit (Quality Assurance - QA) of Banca d´Italia has been in charge of validating size-estimates relevant to multi-year spanning instance contracts. During the years, both estimate and validation documents have been reaching such large volumes and a high level of formalization that workload on the three actors (software development unit, supplier and QA) is continuously raising. In this paper, we describe a simplified estimate process based on a statistical approach, adopted in Banca d´Italia to reduce that workload. This model is applicable only to maintenance activities and it is statistical significant only for estimates smaller then 200 Unadjusted Function Points.