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.