@conference {Izquierdo-Cortazar:2017:UMT:3084226.3084247,
	title = {Using Metrics to Track Code Review Performance},
	booktitle = {Proceedings of the 21st International Conference on Evaluation and Assessment in Software Engineering},
	series = {EASE{\textquoteright}17},
	year = {2017},
	pages = {214{\textendash}223},
	publisher = {ACM},
	organization = {ACM},
	address = {New York, NY, USA},
	abstract = {During 2015, some members of the Xen Project Advisory Board became worried about the performance of their code review process. The Xen Project is a free, open source software project developing one of the most popular virtualization platforms in the industry. They use a pre-commit peer review process similar to that in the Linux kernel, based on email messages. They had observed a large increase over time in the number of messages related to code review, and were worried about how this could be a signal of problems with their code review process.

To address these concerns, we designed and conducted, with their continuous feedback, a detailed analysis focused on finding these problems, if any. During the study, we dealt with the methodological problems of Linux-like code review, and with the deeper issue of finding metrics that could uncover the problems they were worried about. For having a benchmark, we run the same analysis on a similar project, which uses very similar code review practices: the Linux Netdev (Netdev) project. As a result, we learned how in fact the Xen Project had some problems, but at the moment of the analysis those were already under control. We found as well how different the Xen and Netdev projects were behaving with respect to code review performance, despite being so similar from many points of view.

In this paper we show the results of both analyses, and propose a comprehensive methodology, fully automated, to study Linux-style code review. We discuss also the problems of getting significant metrics to track improvements or detect problems in this kind of code review.},
	keywords = {code review, data mining, Software development analytics},
	isbn = {978-1-4503-4804-1},
	doi = {10.1145/3084226.3084247},
	url = {http://doi.acm.org/10.1145/3084226.3084247},
	author = {Izquierdo-Cortazar, Daniel and Sekitoleko, Nelson and Jesus M. Gonzalez-Barahona and Kurth, Lars}
}
@booklet {1781,
	title = {Lessons Learned from Applying Social Network Analysis on an Industrial Free/Libre/Open Source Software Ecosystem},
	year = {2015},
	abstract = {Many software projects are no longer done in-house by a single organization. Instead, we are in a new age where software is developed by a networked community of individuals and organizations, which base their relations to each other on mutual interest. Paradoxically, recent research suggests that software development can actually be jointly-developed by rival firms. For instance, it is known that the mobile-device makers Apple and Samsung kept collaborating in open source projects while running expensive patent wars in the court. Taking a case study approach, we explore how rival firms collaborate in the open source arena by employing a multi-method approach that combines qualitative analysis of archival data (QA) with mining software repositories (MSR) and Social Network Analysis (SNA). While exploring collaborative processes within the OpenStack ecosystem, our research contributes to Software Engineering research by exploring the role of groups, sub-communities and business models within a high-networked open source ecosystem. Surprising results point out that competition for the same revenue model (i.e., operating conflicting business models) does not necessary affect collaboration within the ecosystem. Moreover, while detecting the different sub-communities of the OpenStack community, we found out that the expected social tendency of developers to work with developers from same firm (i.e., homophony) did not hold within the OpenStack ecosystem. Furthermore, while addressing a novel, complex and unexplored open source case, this research also contributes to the management literature in coopetition strategy and high-tech entrepreneurship with a rich description on how heterogeneous actors within a high-networked ecosystem (involving individuals, startups, established firms and public organizations) joint-develop a complex infrastructure for big-data in the open source arena.},
	keywords = {business models, cloud computing, homophily, open source, Open-Coopetition, openstack, social network analysis, Software ecosystems},
	url = {http://arxiv.org/abs/1507.04587},
	author = {Teixeira, Jose and Gregorio Robles and Jesus M. Gonzalez-Barahona}
}
@conference {1694,
	title = {Cream of the crop},
	booktitle = {The International SymposiumProceedings of The International Symposium on Open Collaboration - OpenSym {\textquoteright}14},
	year = {2014},
	pages = {1 - 10},
	publisher = {ACM Press},
	organization = {ACM Press},
	address = {Berlin, GermanyNew York, New York, USA},
	abstract = {In open content communities like Wikipedia and StackOverflow and in open source software projects, a small proportion of users produce a majority of the content and take on much of the required community maintenance work. Understanding this class of users is crucial to creating and sustaining healthy communities. We carried out a mixed-method study of core contributors to the Cyclopath geographic wiki and bicycle routing web site. We present our findings and organize our discussion using concepts from activity theory. We found that the Cyclopath core contributors aren{\textquoteright}t the dedicated cyclists and that the characteristics of the community shape the site, the rules, and the tools for contributing. Additionally, we found that numerous aspects about the surrounding ecology of related systems and communities may help to shape how the site functions and views itself. We draw implications for future research and design from these findings.
},
	isbn = {9781450330169},
	doi = {10.1145/2641580.2641609},
	author = {Katherine Panciera and Mikhil Masli and Loren Terveen}
}
@conference {1692,
	title = {Hackers on Forking},
	booktitle = {The International SymposiumProceedings of The International Symposium on Open Collaboration - OpenSym {\textquoteright}14},
	year = {2014},
	pages = {1 - 10},
	publisher = {ACM Press},
	organization = {ACM Press},
	address = {Berlin, GermanyNew York, New York, USA},
	abstract = {All open source licenses allow the copying of an existing body of code for use as the basis of a separate development project. This practice is commonly known as forking the code. This paper presents the results of a study in which 11 programmers were interviewed about their opinions on the right to fork and the impact of forking on open source software development.

The results show that there is a general consensus among programmers{\textquoteright} views regarding both the favourable and unfavourable aspects that stem from the right to fork. Interestingly, while all programmers noted potential downsides to the right to fork, it was seen by all as an integral component of open source software, and a right that must not be infringed regardless of circumstance or outcome.},
	isbn = {9781450330169},
	doi = {10.1145/2641580.2641590},
	attachments = {https://flosshub.org/sites/flosshub.org/files/p06.pdf},
	author = {Nyman, Linus}
}
@conference {1693,
	title = {Initial Results from the Study of the Open Source Sector in Belgium},
	booktitle = {The International SymposiumProceedings of The International Symposium on Open Collaboration - OpenSym {\textquoteright}14},
	year = {2014},
	pages = {1 - 5},
	publisher = {ACM Press},
	organization = {ACM Press},
	address = {Berlin, GermanyNew York, New York, USA},
	abstract = {The economy of FLOSS (Free and open source software) has been the subject of numerous studies and publications, particularly on the issue of business models. However, there are fewer studies on the local networks of FLOSS providers. This research focuses on the ecosystem of Belgian FLOSS providers and, more specifically, their geographical distribution, the activities, technologies and software they support, their business models, their economic performance and the relationships between companies. The research is based on a directory containing nearly 150 companies. This directory led to the creation of a specialized search engine that helped to improve annotation. The research also uses financial data provided by the Belgian Central Balance Sheet Office. The initial results of this study show a concentration in major economic areas. The businesses are more active in the services and are heavily involved activities such as infrastructure software and Web development, activities which were common in the early years of free software development. Services for the support of business software is also common. A first analysis of the graph of relationships between providers{\textquoteright} websites highlights the role that is played by the multinational IT companies, by FLOSS editors, by commercial FLOSS associations and especially by the Walloon centers of competence that offer vast training catalogs that are dedicated to FLOSS. This research opens up many perspectives for improving the automation of the company directory updates, the analysis of the relationship between enterprises, and the automation of the financial analysis of companies.
},
	isbn = {9781450330169},
	doi = {10.1145/2641580.2641591},
	author = {Viseur, Robert}
}
@conference {1690,
	title = {"The Institutionalization of Digital Openness"},
	booktitle = {The International SymposiumProceedings of The International Symposium on Open Collaboration - OpenSym {\textquoteright}14},
	year = {2014},
	pages = {1 - 2},
	publisher = {ACM Press},
	organization = {ACM Press},
	address = {Berlin, GermanyNew York, New York, USA},
	abstract = {Around the world national and municipal governments launch open data initiatives with declared goals like increased efficiency, transparency or economic growth. However, although little of these effects have been proven, more and more administrations open up their datasets to the public. The dissertation project describes this phenomenon as the ongoing institutionalization of digital openness in the field of public sector information. With empirical evidence from three case studies in large European cities the research project intends to theorize how NGOs, hackers and certain civil servants turn open data into an institution, which more and more public bodies feel the need to adapt to.
},
	isbn = {9781450330169},
	doi = {10.1145/2641580.2641626},
	author = {Maximilian Heimst{\"a}dt}
}
@conference {1691,
	title = {Older Adults and Free/Open Source Software},
	booktitle = {The International SymposiumProceedings of The International Symposium on Open Collaboration - OpenSym {\textquoteright}14},
	year = {2014},
	pages = {1 - 10},
	publisher = {ACM Press},
	organization = {ACM Press},
	address = {Berlin, GermanyNew York, New York, USA},
	abstract = {The global population is aging rapidly, and older adults are becoming increasingly technically savvy. This paper explores ways to engage these individuals to contribute to free/open source software (FOSS) projects. We conducted a pilot diary study to explore motivations, barriers, and the contribution processes of first-time contributors in a real time, qualitative manner. In addition, we measured their self-efficacy before and after their participation. We found that what drove participants were intrinsic motivations, altruism, and internal values, which differed from previous work with older adults and with the general FOSS population. We also found that self-efficacy did not change significantly, even when participants encountered significant barriers or setbacks. The top 3 barriers were lack of communication, installation issues, and documentation issues. We found that asking for and receiving help, and avoiding difficult development environments were more likely to lead to success. To verify these results, we encourage a future large-scale diary study that involves multiple demographics. Given our pilot study, we recommend that future outreach efforts involving older adults focus on how to effectively communicate and build community amongst older contributors.
},
	isbn = {9781450330169},
	doi = {10.1145/2641580.2641589},
	author = {Davidson, Jennifer and Umme Ayda Mannan and Rithika Naik and Ishneet Dua and Jensen, Carlos}
}
@article {1631,
	title = {The evolution of the laws of software evolution},
	journal = {ACM Computing Surveys},
	volume = {46},
	year = {2013},
	month = {11/2013},
	pages = {1 - 28},
	abstract = { After more than 40 years of life, software evolution should be considered as a mature field. However, despite such a long history, many research questions still remain open, and controversial studies about the validity of the laws of software evolution are common. During the first part of these 40 years the laws themselves evolved to adapt to changes in both the research and the software industry environments. This process of adaption to new paradigms, standards, and practices stopped about 15 years ago, when the laws were revised for the last time. However, most controversial studies have been raised during this latter period. Based on a systematic and comprehensive literature review, in this paper we describe how and when the laws, and the software evolution field, evolved. We also address the current state of affairs about the validity of the laws, how they are perceived by the research community, and the developments and challenges that are likely to occur in the coming years.},
	issn = {03600300},
	doi = {10.1145/2543581.2543595},
	attachments = {https://flosshub.org/sites/flosshub.org/files/2013HerraizRRG_CSUR.pdf},
	author = {Herraiz, Israel and Rodriguez, Daniel and Gregorio Robles and Jesus M. Gonzalez-Barahona}
}
@proceedings {1506,
	title = {Intensive Metrics for the Study of the Evolution of Open Source Projects: Case Studies from Apache Software Foundation Projects},
	year = {2013},
	month = {05/2013},
	abstract = {Based on the empirical evidence that the ratio of email messages in public mailing lists to versioning system commits has remained relatively constant along the history of the Apache Software Foundation (ASF), this paper has as goal to study what can be inferred from such a metric for projects of the ASF. We have found that the metric seems to be an intensive metric as it is independent of the size of the project, its activity, or the number of developers, and remains relatively independent of the technology or functional area of the project. Our analysis provides evidence that the metric is related to the technical effervescence and popularity of project, and as such can be a good candidate to measure its healthy evolution. Other, similar metrics -like the ratio of developer messages to commits and the ratio of issue tracker messages to commits- are studied for several projects as well, in order to see if they have similar characteristics.},
	url = {http://oa.upm.es/14698/1/paper.pdf},
	attachments = {https://flosshub.org/sites/flosshub.org/files/paper_1.pdf},
	author = {Gala, Santiago and Gregorio Robles and Jesus M. Gonzalez-Barahona and Herraiz Tabernero, Israel}
}
@book {1541,
	title = {A Preliminary Analysis of Localization in Free Software: How Translations Are Performed},
	series = {IFIP Advances in Information and Communication TechnologyOpen Source Software: Quality Verification},
	volume = {404},
	year = {2013},
	pages = {153 - 167},
	publisher = {Springer Berlin Heidelberg},
	organization = {Springer Berlin Heidelberg},
	address = {Berlin, Heidelberg},
	abstract = {

Software is more than just source code. There is a myriad of elements that compose a software project, among others documentation, translations, multimedia, artwork, marketing. In this paper, we focus on the translation efforts that free, libre, open source software (FLOSS) projects undergo to provide their software in multiple languages. We have therefore analyzed a large amount of projects for their support and procedures regarding translations, if they exist. Our results show that many, but not all, projects offer some type of support and specify some ways to those wanting to contribute. Usually, projects from a more traditional libre software domain are more prone to ease such tasks. However, there is no general way to contribute, as formats and procedures are often project-specific. We have identified as well a high number of translation-supporting tools, with many projects having their own one. All in all, information about how to contribute is the main factor for having a very internationalized application. Projects accepting and giving credit to contributing translators have high levels of internationalization, even if the process is rudimentary.
},
	isbn = {978-3-642-38928-3},
	issn = {1868-422X},
	doi = {10.1007/978-3-642-38928-3_11},
	author = {Reina, Laura Arjona and Gregorio Robles and Jesus M. Gonzalez-Barahona},
	editor = {Petrinja, Etiel and Succi, Giancarlo and Ioini, Nabil and Sillitti, Alberto}
}
@article {gonzalez2013studying,
	title = {Studying the laws of software evolution in a long-lived FLOSS project},
	journal = {Journal of Software: Evolution and Process},
	year = {2013},
	publisher = {Wiley Online Library},
	abstract = {Some free, open-source software projects have been around for quite a long time, the longest living ones dating from the early 1980s. For some of them, detailed information about their evolution is available in source code management systems tracking all their code changes for periods of more than 15 years. This paper examines in detail the evolution of one of such projects, glibc, with the main aim of understanding how it evolved and how it matched Lehman{\textquoteright}s laws of software evolution. As a result, we have developed a methodology for studying the evolution of such long-lived projects based on the information in their source code management repository, described in detail several aspects of the history of glibc, including some activity and size metrics, and found how some of the laws of software evolution may not hold in this case.},
	url = {http://oa.upm.es/21355/1/smr1615.pdf},
	author = {Jesus M. Gonzalez-Barahona and Gregorio Robles and Herraiz, Israel and Ortega, Felipe}
}
@article {1706,
	title = {Trends in Free, Libre, Open Source Software Communities: From Volunteers to Companies / Aktuelle Trends in Free-, Libre-, und Open-Source-Software-Gemeinschaften: Von Freiwilligen zu Unternehmen},
	journal = {it - Information Technology},
	volume = {55},
	year = {2013},
	month = {01/2013},
	abstract = {The first free/libre/open source software (FLOSS)
development communities were composed almost exclusively
of volunteers. They were individuals who, despite their
affiliation, contributed to the project on their own. They
decided which project to join, and their contributions were
personal in nature, even when in some cases they were
employees of companies with some interests in the project.
GNU, the first of such communities, and some others that
emerged during the late 1980s and 1990s, followed this
pattern. During the 1990s corporate interests started to
have a role in some FLOSS communities. Companies hired
people from those communities to gain influence, or tasked
their employees to contribute to them, again with the idea
of influencing their decisions. During the 2000s, corporate
communities, in which companies are first-class citizens,
have emerged, changing the rules and redefining the role of
volunteers and non-affiliated individuals. However, the role
of developers, with independence of the company for which
they work, is still important even in these communities.
This paper addresses this transition from volunteer-based
to company-based development communities, and explores
the structure and behavior of the latter.},
	issn = {1611-2776},
	doi = {10.1524/itit.2013.1012},
	url = {http://dirkriehle.com/wp-content/uploads/2013/10/itit.2013.1012.pdf},
	attachments = {https://flosshub.org/sites/flosshub.org/files/itit.2013.1012.pdf},
	author = {Jesus M. Gonzalez-Barahona and Gregorio Robles}
}
@article {1810,
	title = {Understanding How Companies Interact with Free Software Communities},
	journal = {IEEE Software},
	volume = {30},
	year = {2013},
	month = {9/2013},
	pages = {38 - 45},
	abstract = {When free, open source software development communities work with companies that use their output, it{\textquoteright}s especially important for both parties to understand how this collaboration is performing. The use of data analytics techniques on software development repositories can improve factual knowledge about performance metrics.
},
	issn = {0740-7459},
	doi = {10.1109/MS.2013.95},
	author = {Jesus M. Gonzalez-Barahona and Izquierdo-Cortazar, Daniel and Maffulli, Stefano and Gregorio Robles}
}
@article {1324,
	title = {Are Developers Fixing Their Own Bugs?},
	journal = {International Journal of Open Source Software and Processes},
	volume = {3},
	year = {2011},
	note = {"The analysis is focused at the level of lines of code and it uses the information stored in the source code management system"},
	pages = {23 - 42},
	abstract = {The process of fixing software bugs plays a key role in the maintenance activities of a software project. Ideally, code ownership and responsibility should be enforced among developers working on the same artifacts, so that those introducing buggy code could also contribute to its fix. However, especially in FLOSS projects, this mechanism is not clearly understood: in particular, it is not known whether those contributors fixing a bug are the same introducing and seeding it in the first place. This paper analyzes the comm-central FLOSS project, which hosts part of the Thunderbird, SeaMonkey, Lightning extensions and Sunbird projects from the Mozilla community. The analysis is focused at the level of lines of code and it uses the information stored in the source code management system. The results of this study show that in 80\% of the cases, the bug-fixing activity involves source code modified by at most two developers. It also emerges that the developers fixing the bug are only responsible for 3.5\% of the previous modifications to the lines affected; this implies that the other developers making changes to those lines could have made that fix. In most of the cases the bug fixing process in comm-central is not carried out by the same developers than those who seeded the buggy code.},
	keywords = {bug fixing, developers, loc, scm},
	issn = {1942-3934},
	doi = {10.4018/jossp.2011040102},
	author = {Izquierdo-Cortazar, Daniel and Capiluppi, Andrea and Jesus M. Gonzalez-Barahona}
}
@article {1219,
	title = {Repositories with Public Data about Software Development},
	journal = {International Journal of Open Source Software and Processes},
	volume = {2},
	year = {2010},
	month = {04/2010},
	pages = {1 - 13},
	abstract = {Empirical research on software development based on data obtained from project repositories and code forges is increasingly gaining attention in the software engineering research community. The studies in this area typically start by retrieving or monitoring some subset of data found in the repository or forge, and this data is later analyzed to find interesting patterns. However, retrieving information from these locations can be a challenging task. Meta-repositories providing public information about software development are useful tools that can simplify and streamline the research process. Public data repositories that collect and clean the data from other project repositories or code forges can help ensure that research studies are based on good quality data. This paper provides some insight as to how these meta-repositories (sometimes called a {\textquotedblleft}repository of repositories{\textquotedblright}, RoR) of data about open source projects should be used to help researchers. This paper describes in detail two of the most widely used collections of data about software development: FLOSSmole and FLOSSMetrics.},
	issn = {1942-3934},
	doi = {10.4018/jossp.2010040101},
	attachments = {https://flosshub.org/sites/flosshub.org/files/ijossp2010.pdf},
	author = {Jesus M. Gonzalez-Barahona and Izquierdo-Cortazar, Daniel and Squire, Megan}
}
@conference {941,
	title = {Evolution of the core team of developers in libre software projects},
	booktitle = {2009 6th IEEE International Working Conference on Mining Software Repositories (MSR)2009 6th IEEE International Working Conference on Mining Software Repositories},
	year = {2009},
	pages = {167 - 170},
	publisher = {IEEE},
	organization = {IEEE},
	address = {Vancouver, BC, Canada},
	abstract = {In many libre (free, open source) software projects, most of the development is performed by a relatively small number of persons, the "core team". The stability and permanence of this group of most active developers is of great importance for the evolution and sustainability of the project. In this position paper we propose a quantitative methodology to study the evolution of core teams by analyzing information from source code management repositories. The most active developers in different periods are identified, and their activity is calculated over time, looking for core team evolution patterns.},
	keywords = {core, cvs, cvsanaly, developers, evolution, gimp, scm},
	isbn = {978-1-4244-3493-0},
	doi = {10.1109/MSR.2009.5069497},
	attachments = {https://flosshub.org/sites/flosshub.org/files/167core-evolution.pdf},
	author = {Gregorio Robles and Jesus M. Gonzalez-Barahona and Herraiz, Israel}
}
@article {10.1109/HICSS.2009.1014,
	title = {Using Software Archaeology to Measure Knowledge Loss in Software Projects Due to Developer Turnover},
	journal = {2009 42nd Hawaii International Conference on System Sciences (HICSS 2009)},
	year = {2009},
	pages = {1-10},
	publisher = {IEEE Computer Society},
	address = {Los Alamitos, CA, USA},
	abstract = {Developer turnover can result in a major problem when developing software. When senior developers abandon a software project, they leave a knowledge gap that has to be managed. In addition, new (junior) developers require some time in order to achieve the desired level of productivity. In this paper, we present a methodology to measure the effect of knowledge loss due to developer turnover in software projects. For a given software project, we measure the quantity of code that has been authored by developers that do not belong to the current development team, which we define as orphaned code. Besides, we study how orphaned code is managed by the project. Our methodology is based on the concept of software archaeology, a derivation of software evolution. As case studies we have selected four FLOSS (free, libre, open source software) projects, from purely driven by volunteers to company-supported. The application of our methodology to these case studies will give insight into the turnover that these projects suffer and how they have managed it and shows that this methodology is worth being augmented in future research.},
	keywords = {attrition, case study, developers, evince, evolution, gimp, growth, knowledge collaboration, lines of code, nautilus, quality, sloc, turnover},
	isbn = {978-0-7695-3450-3},
	doi = {http://doi.ieeecomputersociety.org/10.1109/HICSS.2009.1014},
	attachments = {https://flosshub.org/sites/flosshub.org/files/07-07-08.pdf},
	author = {Izquierdo-Cortazar, Daniel and Gregorio Robles and Ortega, Felipe and Jesus M. Gonzalez-Barahona}
}
@article {GonzalezBarahona2008356,
	title = {Geographic origin of libre software developers},
	journal = {Information Economics and Policy},
	volume = {20},
	number = {4},
	year = {2008},
	note = {Empirical Issues in Open Source Software},
	pages = {356 - 363},
	abstract = {This paper examines the claim that libre (free, open source) software involves global development. The anecdotal evidence is that developers usually work in teams including individuals residing in many different geographical areas, time zones and even continents and that, as a whole, the libre software community is also diverse in terms of national origin. However, its exact composition is difficult to capture, since there are few records of the geographical location of developers. Past studies have been based on surveying a limited (and sometimes biased) sample and extrapolating that sample to the global distribution of developers. In this paper we present an alternate approach in which databases are analyzed to create traces of information from which the geographical origin of developers can be inferred. Applying this technique to the SourceForge users database and the mailing lists archives from several large projects, we have estimated the geographical origin of more than one million individuals who are closely related to the libre software development process. The paper concludes that the result is a good proxy for the actual distribution of libre software developers working on global projects.},
	keywords = {developers, email, email address, email archives, geography, mailing list, open source software, sourceforge, timezone, users},
	issn = {0167-6245},
	doi = {DOI: 10.1016/j.infoecopol.2008.07.001},
	url = {http://www.sciencedirect.com/science/article/B6V8J-4T3DCPK-1/2/3981dfbc523eae1d1ce65fb1f0c0edb7},
	author = {Jesus M. Gonzalez-Barahona and Gregorio Robles and Roberto Andradas-Izquierdo and Rishab Aiyer Ghosh}
}
@conference {Herraiz:2008:TSB:1370750.1370786,
	title = {Towards a simplification of the bug report form in eclipse},
	booktitle = {Proceedings of the 2008 international working conference on Mining software repositories},
	series = {MSR {\textquoteright}08},
	year = {2008},
	pages = {145{\textendash}148},
	publisher = {ACM},
	organization = {ACM},
	address = {New York, NY, USA},
	abstract = {We believe that the bug report form of Eclipse contains too many fields, and that for some fields, there are too many options. In this MSR challenge report, we focus in the case of the severity field. That field contains seven different levels of severity. Some of them seem very similar, and it is hard to distinguish among them. Users assign severity, and developers give priority to the reports depending on their severity. However, if users can not distinguish well among the various severity options, they will probably assign different priorities to bugs that require the same priority. We study the mean time to close bugs reported in Eclipse, and how the severity assigned by users affects this time. The results shows that classifying by time to close, there are less clusters of bugs than levels of severity. We therefore conclude that there is a need to make a simpler bug report form.},
	keywords = {bug fixing, bug report, bug tracking system, classification, eclipse, msr challenge, severity},
	isbn = {978-1-60558-024-1},
	doi = {http://doi.acm.org/10.1145/1370750.1370786},
	url = {http://doi.acm.org/10.1145/1370750.1370786},
	author = {Herraiz, Israel and Daniel M. German and Jesus M. Gonzalez-Barahona and Gregorio Robles}
}
@conference {1017,
	title = {Forecasting the Number of Changes in Eclipse Using Time Series Analysis},
	booktitle = {Fourth International Workshop on Mining Software Repositories (MSR{\textquoteright}07:ICSE Workshops 2007)},
	year = {2007},
	pages = {32 - 32},
	publisher = {IEEE},
	organization = {IEEE},
	address = {Minneapolis, MN, USA},
	abstract = {In order to predict the number of changes in the following months for the project Eclipse, we have applied a statistical (non-explanatory) model based on time series analysis. We have obtained the monthly number of changes in the CVS repository of Eclipse, using the CVSAnalY tool. The input to our model was the filtered series of the number of changes per month, and the output was the number of changes per month for the next three months. Then we aggregated the results of the three months to obtain the total number of changes in the given period in the challenge.},
	keywords = {change management, cvs, cvsanaly, eclipse, prediction},
	isbn = {0-7695-2950-X},
	doi = {10.1109/MSR.2007.10},
	attachments = {https://flosshub.org/sites/flosshub.org/files/28300032.pdf},
	author = {Herraiz, Israel and Jesus M. Gonzalez-Barahona and Gregorio Robles}
}
@conference {1013,
	title = {Impact of the Creation of the Mozilla Foundation in the Activity of Developers},
	booktitle = {Fourth International Workshop on Mining Software Repositories (MSR{\textquoteright}07:ICSE Workshops 2007)},
	year = {2007},
	pages = {28 - 28},
	publisher = {IEEE},
	organization = {IEEE},
	address = {Minneapolis, MN, USA},
	abstract = {During 2003, the Mozilla project transitioned from company-promoted (sponsored by AOL) to community-promoted (sponsored by the Mozilla Foundation). What happened to the group of developers during this transition? There was any significant impact on its activity or composition? To answer these questions, we have performed an analysis of the CVS repository of Mozilla, using the CVSAnalY tool, finding little on activity, but dramatic changes in the the composition of the development team.},
	keywords = {cvs, cvsanaly, developers, mining challenge, mozilla, msr challenge, revision history},
	isbn = {0-7695-2950-X},
	doi = {10.1109/MSR.2007.15},
	attachments = {https://flosshub.org/sites/flosshub.org/files/28300028.pdf},
	author = {Jesus M. Gonzalez-Barahona and Gregorio Robles and Herraiz, Israel}
}
@conference {1006,
	title = {Towards a Theoretical Model for Software Growth},
	booktitle = {Fourth International Workshop on Mining Software Repositories (MSR{\textquoteright}07:ICSE Workshops 2007)},
	year = {2007},
	pages = {21 - 21},
	publisher = {IEEE},
	organization = {IEEE},
	address = {Minneapolis, MN, USA},
	abstract = {Software growth (and more broadly, software evolution) is usually considered in terms of size or complexity of source code. However in different studies, usually different metrics are used, which make it difficult to compare approaches and results. In addition, not all metrics are equally easy to calculate for a given source code, which leads to the question of which one is the easiest to calculate without losing too much information. To address both issues, in this paper present a comprehensive study, based on the analysis of about 700,000 C source code files, calculating several size and complexity metrics for all of them. For this sample, we have found double Pareto statistical distributions for all metrics considered, and a high correlation between any two of them. This would imply that any model addressing software growth should produce this Pareto distributions, and that analysis based on any of the considered metrics should show a similar pattern, provided the sample of files considered is large enough.},
	keywords = {C, complexity, evolution, freebsd, growth, halstead, lines of code, loc, mccabe, metrics, scm, size, sloc, sloccount, source code},
	isbn = {0-7695-2950-X},
	doi = {10.1109/MSR.2007.31},
	attachments = {https://flosshub.org/sites/flosshub.org/files/28300021.pdf},
	author = {Herraiz, Israel and Jesus M. Gonzalez-Barahona and Gregorio Robles}
}
@article {120,
	title = {Applying Social Network Analysis Techniques to Community-Driven Libre Software Projects},
	journal = {International Journal of Information Technology and Web Engineering},
	volume = {1},
	number = {3},
	year = {2006},
	abstract = {Source code management repositories of large, long-lived libre (free, open source) software projects can be a source of valuable data about the organizational structure, evolution, and knowledge exchange in the corresponding development communities. Unfortunately, the sheer volume of the available information renders it almost unusable without applying methodologies which highlight the relevant information for a given aspect of the project. Such methodology is proposed in this article, based on well known concepts from the social networks analysis field, which can be used to study the relationships among developers and how they collaborate in different parts of a project. It is also applied to data mined from some well known projects (Apache, GNOME, and KDE), focusing on the characterization of their collaboration network architecture. These cases help to understand the potentials of the methodology and how it is applied, but also shows some relevant results which open new paths in the understanding of the informal organization of libre software development communities.},
	keywords = {apache, conway{\textquoteright}s law, cvs, gnome, kde, scm, social network analysis, source code},
	attachments = {https://flosshub.org/sites/flosshub.org/files/06_Lopez_ijitwe_sna.pdf},
	author = {L{\'o}pez-Fern{\'a}ndez, L. and Gregorio Robles and Jesus M. Gonzalez-Barahona and Herraiz, I.}
}
@conference {Amor:2006:EEC:1139113.1139116,
	title = {Effort Estimation by Characterizing Developer Activity},
	booktitle = {Proceedings of the 2006 International Workshop on Economics Driven Software Engineering Research},
	series = {EDSER {\textquoteright}06},
	year = {2006},
	pages = {3{\textendash}6},
	publisher = {ACM},
	organization = {ACM},
	address = {New York, NY, USA},
	abstract = {During the latest years libre (free, open source) software has gained a lot of attention from the industry. Following this interest, the research community is also studying it. For instance, many teams are performing quantitative analysis on the large quantity of data which is publicly available from the development repositories maintained by libre software projects. However, not much of this research is focused on cost or effort estimations, despite its importance (for instance, for companies developing libre software or collaborating with libre software projects), and the availability of some data which could be useful for this purpose. Our position is that classical effort estimation models can be improved from the study of these data, at least when applied to libre software. In this paper, we focus on the characterization of developer activity, which we argue can improve effort estimation. This activity can be traced with a lot of detail, and the resulting data can also be used for validation of any effort estimation model.
},
	keywords = {developer characterization, effort estimation, mining software repositories, open source software, software economics},
	isbn = {1-59593-396-4},
	doi = {10.1145/1139113.1139116},
	url = {http://doi.acm.org/10.1145/1139113.1139116},
	author = {Amor, Juan Jose and Gregorio Robles and Jesus M. Gonzalez-Barahona}
}
@conference {Robles:2006:GLD:1137983.1138017,
	title = {Geographic location of developers at SourceForge},
	booktitle = {Proceedings of the 2006 international workshop on Mining software repositories},
	series = {MSR {\textquoteright}06},
	year = {2006},
	pages = {144{\textendash}150},
	publisher = {ACM},
	organization = {ACM},
	address = {New York, NY, USA},
	abstract = {The development of libre (free/open source) software is usually performed by geographically distributed teams. Participation in most cases is voluntary, sometimes sporadic, and often not framed by a pre-defined management structure. This means that anybody can contribute, and in principle no national origin has advantages over others, except for the differences in availability and quality of Internet connections and language. However, differences in participation across regions do exist, although there are little studies about them. In this paper we present some data which can be the basis for some of those studies. We have taken the database of users registered at SourceForge, the largest libre software development web-based platform, and have inferred their geographical locations. For this, we have applied several techniques and heuristics on the available data (mainly e-mail addresses and time zones), which are presented and discussed in detail. The results show a snapshot of the regional distribution of SourceForge users, which may be a good proxy of the actual distribution of libre software developers. In addition, the methodology may be of interest for similar studies in other domains, when the available data is similar (as is the case of mailing lists related to software projects).},
	keywords = {distributed, email, email address, free software, geographical location, geography, libre software, mining software repositories, open source software, sourceforge, timezone},
	isbn = {1-59593-397-2},
	doi = {http://doi.acm.org/10.1145/1137983.1138017},
	url = {http://doi.acm.org/10.1145/1137983.1138017},
	attachments = {https://flosshub.org/sites/flosshub.org/files/144GeographicLocation.pdf},
	author = {Gregorio Robles and Jesus M. Gonzalez-Barahona}
}
@conference {Robles:2006:MLS:1137983.1137986,
	title = {Mining large software compilations over time: another perspective of software evolution},
	booktitle = {Proceedings of the 2006 international workshop on Mining software repositories},
	series = {MSR {\textquoteright}06},
	year = {2006},
	pages = {3{\textendash}9},
	publisher = {ACM},
	organization = {ACM},
	address = {New York, NY, USA},
	abstract = {With the success of libre (free, open source) software, a new type of software compilation has become increasingly common. Such compilations, often referred to as {\textquoteright}distributions{\textquoteright}, group hundreds, if not thousands, of software applications and libraries written by independent parties into an integrated system. Software compilations raise a number of questions that have not been targeted so far by software evolution, which usually focuses on the evolution of single applications. Undoubtedly, the challenges that software compilations face differ from those found in single software applications. Nevertheless, it can be assumed that both, the evolution of applications and that of software compilations, have similarities and dependencies.In this sense, we identify a dichotomy, common to that in economics, of software evolution in the small (micro-evolution) and in the large (macro-evolution). The goal of this paper is to study the evolution of a large software compilation, mining the publicly available repository of a well-known Linux distribution, Debian. We will therefore investigate changes related to hundreds of millions of lines of code over seven years. The aspects that will be covered in this paper are size (in terms of number of packages and of number of lines of code), use of programming languages, maintenance of packages and file sizes.},
	keywords = {debian, distributions, evolution, large software collections, lines of code, loc, metrics, mining software repositories, size, sloc, sloccount, software evolution, software integrators},
	isbn = {1-59593-397-2},
	doi = {http://doi.acm.org/10.1145/1137983.1137986},
	url = {http://doi.acm.org/10.1145/1137983.1137986},
	attachments = {https://flosshub.org/sites/flosshub.org/files/3miningLarge.pdf},
	author = {Gregorio Robles and Jesus M. Gonzalez-Barahona and Martin Michlmayr and Amor, Juan Jose}
}
@conference {Robles:2005:DIM:1083142.1083162,
	title = {Developer identification methods for integrated data from various sources},
	booktitle = {Proceedings of the 2005 international workshop on Mining software repositories},
	series = {MSR {\textquoteright}05},
	year = {2005},
	pages = {106-110},
	publisher = {ACM},
	organization = {ACM},
	address = {New York, NY, USA},
	abstract = {Studying a software project by mining data from a single repository has been a very active research field in software engineering during the last years. However, few efforts have been devoted to perform studies by integrating data from various repositories, with different kinds of information, which would, for instance, track the different activities of developers. One of the main problems of these multi-repository studies is the different identities that developers use when they interact with different tools in different contexts. This makes them appear as different entities when data is mined from different repositories (and in some cases, even from a single one). In this paper we propose an approach, based on the application of heuristics, to identify the many identities of developers in such cases, and a data structure for allowing both the anonymized distribution of information, and the tracking of identities for verification purposes. The methodology will be presented in general, and applied to the GNOME project as a case example. Privacy issues and partial merging with new data sources will also be considered and discussed.},
	keywords = {anonymization, bug tracker, developers, email, email address, gnome, identity, mailing list, privacy, source code, version control},
	isbn = {1-59593-123-6},
	doi = {http://doi.acm.org/10.1145/1082983.1083162},
	url = {http://doi.acm.org/10.1145/1082983.1083162},
	attachments = {https://flosshub.org/sites/flosshub.org/files/106DeveloperIdentification.pdf},
	author = {Gregorio Robles and Jesus M. Gonzalez-Barahona}
}
@conference {Robles05anempirical,
	title = {An empirical approach to Software Archaeology},
	booktitle = {In: Poster Proceedings of the International Conference on Software Maintenance},
	year = {2005},
	pages = {47{\textendash}50},
	abstract = {The term {\textquotedblleft}software archaeology {\textquotedblright} provides a useful metaphor of the tasks that a software developer has to face when performing maintenance on large software projects. The source code of a program at any point in time is the result of many different changes performed in the past, usually by several people, which can be tracked when a version control system is used. We have designed a methodology for analyzing with detail the age of the source code in such cases, and have applied it to several large software projects. As a part of the methodology, we define a set of indexes which can help to characterize the history of a software system, and discuss how those could be used to estimate its past and future maintenance. We also show how our approach to software archaeology is simple both conceptually and computationally, but still very powerful at uncovering useful information.},
	author = {Gregorio Robles and Jesus M. Gonzalez-Barahona and Herraiz, Israel}
}
@article {130,
	title = {Evolution and growth in large libre software projects},
	journal = {Principles of Software Evolution, Eighth International Workshop on},
	year = {2005},
	pages = {165-174},
	author = {Gregorio Robles and Amor, J. J. and Jesus M. Gonzalez-Barahona and Herraiz, I.}
}
@conference {731,
	title = {Evolution of Volunteer Participation in Libre Software Projects: Evidence from Debian},
	booktitle = {OSS2005: Open Source Systems },
	year = {2005},
	note = {"For each release we have retrieved the corresponding sources.gz file (see below) from the Debian archive. From it we have extracted information about the packages and their maintainers...."
},
	pages = {100-107},
	abstract = {Most libre software projects rely on the work of volunteers. Therefore, attracting people who contribute their time and technical skills is of paramount importance, both in technical and economic terms. This reliance on volunteers leads to some fundamental management challenges: volunteer contributions are inherently difficult to predict, plan and manage, especially in the case of large projects. In this paper we analyze the evolution in time of the human resources of one of the largest and most complex libre software projects composed primarily of volunteers, the Debian project. Debian currently has around 1300 volunteers working on several tasks: much activity is focused on packaging software applications and libraries, but there is also major work related to the maintenance of the infrastructure needed to sustain the development. We have performed a quantitative investigation of data from almost seven years, studying how volunteer involvement has affected the software...},
	keywords = {contributors, debian, maintainers, PopCon, popularity, Volunteers},
	url = {http://pascal.case.unibz.it/handle/2038/857},
	attachments = {https://flosshub.org/sites/flosshub.org/files/robles_barahona_michlmayr-evolution_participation.pdf},
	author = {Gregorio Robles and Jesus M. Gonzalez-Barahona and Martin Michlmayr}
}
@booklet {Lopez-Fernandez_applyingsocial,
	title = {Applying Social Network Analysis to the Information in CVS Repositories},
	howpublished = {International Workshop on Mining Software Repositories (MSR 2004)},
	year = {2004},
	pages = {101-105},
	abstract = {The huge quantities of data available in the CVS repositories of large, long-lived libre (free, open source) software projects, and the many interrelationships among those data offer opportunities for extracting large amounts of valuable information about their structure, evolution and internal processes. Unfortunately, the sheer volume of that information renders it almost unusable without applying methodologies which highlight the relevant information for a given aspect of the project. In this paper, we propose the use of a well known set of methodologies (social network analysis) for characterizing libre software projects, their evolution over time and their internal structure. In addition, we show how we have applied such methodologies to real cases, and extract some preliminary conclusions from that experience.},
	keywords = {apache, complex networks, cvs, gnome, kde, libre software engineering, source code, source code repositories, visualization techniques, vizualization},
	attachments = {https://flosshub.org/sites/flosshub.org/files/101ApplyingSocial.pdf},
	author = {L{\'o}pez-Fern{\'a}ndez, L. and Gregorio Robles and Jesus M. Gonzalez-Barahona}
}
@proceedings {1190,
	title = {Community structure of modules in the Apache project},
	year = {2004},
	pages = {44-48},
	abstract = {The relationships among modules in a software project of a certain size can give us much information about its internal organization and a way to control and monitor development activities and evolution of large libre software projects. In this paper, we show how information available in CVS repositories can be used to study the structure of the modules in a project when they are related by the people working in them, and how techniques taken from the social networks fields can be used to highlight the characteristics of that structure. As a case example, we also show some results of applying this methodology to the Apache project in several points in time. Among other facts, it is shown how the project evolves and is self-structuring, with developer communities of modules corresponding to semantically related families of modules.},
	keywords = {apache, cvs, source code},
	attachments = {https://flosshub.org/sites/flosshub.org/files/gonzalezBarahona44-48.pdf},
	author = {Jesus M. Gonzalez-Barahona and Luis Lopez and Gregorio Robles}
}
@article {flosswp174,
	title = {Community structure of modules in the Apache project},
	year = {2004},
	month = {June},
	abstract = {The relationships among modules in a software project of a certain size can give us much information about its internal organization and a way to control and monitor development activities and evolution of large libre software projects. In this paper, we show how information available in CVS repositories can be used to study the structure of the modules in a project when they are related by the people working in them, and how techniques taken from the social networks fields can be used to highlight the characteristics of that structure. As a case example, we also show some results of applying this methodology to the Apache project in several points in time. Among other facts, it is shown how the project evolves and is self-structuring, with developer communities of modules corresponding to semantically related families of modules.},
	attachments = {https://flosshub.org/sites/flosshub.org/files/barahona-apache_structure.pdf},
	author = {Jesus M. Gonzalez-Barahona}
}
@article {flosswp178,
	title = {GlueTheos: Automating the Retrieval and Analysis of Data from Publicly Available Software Repositories},
	journal = {Proceedings of the 2004 international workshop on Mining software repositories  - MSR {\textquoteright}04},
	year = {2004},
	month = {05/2004},
	abstract = {For efficient, large scale data mining of publicly available information about libre (free, open source) software projects, automating the retrieval and analysis processes is a must. A system implementing such automation must have into account the many kinds of repositories with interesting information (each with its own structure and access methods), and the many kinds of analysis which can be applied to the retrieved data. In addition, such a system should be capable of interfacing and reusing as much existing software for both retrieving and analyzing data as possible. As a proof of concept of how that system could be, we started sometime ago to implement the GlueTheos system, featuring a modular,flexible architecture which has been already used in several of our studies of libre software projects. In this paper we show its structure, how it can be used, and how it can be extended.},
	attachments = {https://flosshub.org/sites/flosshub.org/files/robles-barahona-ghosh_gluetheos.pdf},
	author = {Gregorio Robles and Jesus M. Gonzalez-Barahona and Rishab Ayer Ghosh}
}
@proceedings {131,
	title = {Remote analysis and measurement of libre software systems by means of the CVSanaly tool},
	year = {2004},
	address = {Edinburgh, Scotland},
	abstract = {Libre (free, open source) software is one of the paradigmatic cases where heavy use of telematic tools and user-driven software development are key points. This paper proposes a methodology for measuring and analyzing remotely big libre software projects using publicly-available data from their version control repositories. By means of a tool called CVSAnalY that has been implemented following this methodology, measurements and analyses can be made in an automatic and non-intrusive way, providing real-time and historical data about the project and its contributors.},
	attachments = {https://flosshub.org/sites/flosshub.org/files/robles-koch-barahona_cvsanaly.pdf},
	author = {Gregorio Robles and Koch, Stefan and Jesus M. Gonzalez-Barahona}
}
@article {flosswp116,
	title = {Free software engineering: A field to explore},
	year = {2003},
	month = {September},
	abstract = {The challenge of free software is not that of a new competitor who, under the same rules, produces software faster, cheaper and of a better quality. Free software differs from "traditional" software in more fundamental aspects, starting with philosophical reasons and motivations, continuing with new economic and market rules and ending up with a different way of producing software. Software Engineering cannot ignore this phenomenon, and the last five years or so has seen ever more research into all these issues. This article takes a look at the most significant studies in this field and the results they are producing, with a view to providing the reader with a vision of the state of the art and the future prospects of what we have come to call free Software Engineering.},
	attachments = {https://flosshub.org/sites/flosshub.org/files/barahonarobles.pdf},
	author = {Jesus M. Gonzalez-Barahona}
}
@proceedings {1178,
	title = {Studying the evolution of libre software projects using publicly available data},
	year = {2003},
	month = {2003},
	pages = {111-115},
	attachments = {https://flosshub.org/sites/flosshub.org/files/111-115.pdf},
	author = {Gregorio Robles and Jesus M. Gonzalez-Barahona and Jose Centeno-Gonz{\'a}lez and Vicente Matellan-Olivera and Luis Rodero-Merino}
}
@article {flosswp53,
	title = {Counting potatoes: The size of Debian 2.2},
	year = {2002},
	month = {March},
	abstract = {Debian is possibly the largest free software distribution, with well over 2,800 source packages in the latest stable release (Debian 2.2) and more than 4,000 source packages in the release currently in preparation. But, how large is "the largest"? We show that Debian 2.2 includes more than 55,000,000 physical SLOC (almost twice than Red Hat 7.1, released about 8 months later), showing that the Debian development model (based on the work of a large group of voluntary developers spread around the world) is at least as capable as other development methods (like the more centralized one) to manage distributions of this size. It is also shown that if Debian had been developed using traditional proprietary methods, that its cost would be close to $1.9 billion. In addition, we offer both an analysis of the programming languages used in the distribution.},
	attachments = {https://flosshub.org/sites/flosshub.org/files/counting-potatoes.html},
	author = {Jesus M. Gonzalez-Barahona}
}
