Cross-company and single-company effort models using the ISBSG database: a further replicated study

Abstract

Five years ago the ISBSG database was used by Jeffery et al. [6] (S1) to compare the effort prediction accuracy between cross- and single-company effort models. Given that more than 2,000 projects were later volunteered to this database, in 2005 Mendes et al. [17] (S2) replicated S1 but obtained different results. The difference in results between both studies could have resulted from legitimate differences in data set patterns but also could have been influenced by differences in experimental procedure. S2 was unable to employ exactly the same experimental procedure used in S1, as S1's procedure was not fully documented. Therefore this paper aimed to apply S2's experimental procedure to the ISBSG database version used in S1 (release 6) to assess if differences in experimental procedure would have contributed towards different results. Our results corroborated those from S1: we found that predictions based on a single-company model were significantly more accurate than those based on a cross-company model.