@conference {Robles:2014:EDE:2597073.2597107, title = {Estimating Development Effort in Free/Open Source Software Projects by Mining Software Repositories: A Case Study of OpenStack}, booktitle = {Proceedings of the 11th Working Conference on Mining Software Repositories}, series = {MSR 2014}, year = {2014}, pages = {222{\textendash}231}, publisher = {ACM}, organization = {ACM}, address = {New York, NY, USA}, abstract = {Because of the distributed and collaborative nature of free / open source software (FOSS) projects, the development effort invested in a project is usually unknown, even after the software has been released. However, this information is becoming of major interest, especially ---but not only--- because of the growth in the number of companies for which FOSS has become relevant for their business strategy. In this paper we present a novel approach to estimate effort by considering data from source code management repositories. We apply our model to the OpenStack project, a FOSS project with more than 1,000 authors, in which several tens of companies cooperate. Based on data from its repositories and together with the input from a survey answered by more than 100 developers, we show that the model offers a simple, but sound way of obtaining software development estimations with bounded margins of error. }, keywords = {effort estimation, free software, mining software repositories, open source, openstack}, isbn = {978-1-4503-2863-0}, doi = {10.1145/2597073.2597107}, url = {http://doi.acm.org/10.1145/2597073.2597107}, attachments = {https://flosshub.org/sites/flosshub.org/files/robles_0.pdf}, author = {Gregorio Robles and Gonz{\'a}lez-Barahona, Jes{\'u}s M. and Cervig{\'o}n, Carlos and Capiluppi, Andrea and Izquierdo-Cort{\'a}zar, Daniel} }