Four years ago was the last time the ISBSG database was used to compare the effort prediction accuracy between cross-company and within-company cost models. Since then more than 2,000 projects have been volunteered to this database, which may have changed the trends previously observed. This paper therefore replicates a previous study by investigating how successful a cross-company cost model is: i) to estimate effort for projects that belong to a single company and were not used to build the cross-company model; ii) compared to a within-company cost model. Our within-company data set had data on 184 software projects from a single company and our cross-company data set employed data on 672 software projects.

Our results did not corroborate those from the previous study, showing that predictions based on the within-company model were not significantly more accurate than those based on the cross-company model. We analysed the data using forward stepwise regression.