Cross-company vs. single-company Web effort models using the Tukutuku database: an extended study

In 2004 Kitchenham and Mendes with study (S1) investigated, using data on 63 Web projects, to what extent a cross-company cost model could be successfully employed to estimate development effort for single-company Web projects. Their effort models were built using Forward Stepwise Regression (SWR) and they found that cross-company predictions were significantly worse than single-company predictions. This study S1 was extended by (S2) [Mendes and Kitchenham 2004], who used SWR and Case-based reasoning (CBR), and data on 67 Web projects from the Tukutuku database. They built two cross-company and one single-company models and found that both SWR cross-company models and CBR cross-company data provided predictions significantly worse than single-company predictions. Since 2004 another 83 projects were volunteered to the Tukutuku database, and recently used in study (S3) [Mendes, E., Di Martino, S., Ferrucci, F., Gravino, C., 2007], who partially replicated Mendes and Kitchenham's study (S2), using SWR and CBR. They corroborated some of S2's findings (SWR cross-company model and the CBR cross-company data provided predictions significantly worse than single-company predictions) however they replicated only part of S2. The objective of this paper is therefore to extend Mendes et al.'s work and fully replicate S2. We used the same dataset used in S3, and our results corroborated most of those obtained in S2. The main difference between S2 and our study was that one of our SWR cross-company models showed significantly similar predictions to the single-company model, which contradicts the findings from S2