Determinants of Output Per Contributor in Open Source Projects, The: An Empirical Examination

Intellectual Property and Open Source

Article Snapshot


Chaim Fershtman and Neil Gandal


CEPR Discussion Paper No. 4329, March 2004


This paper asks what motivates programmers to contribute code to open source projects with little commercial potential.

Policy Relevance

Learning how open source software development works helps policymakers avoid idealizing one model of innovation at the expense of traditional proprietary models.

Main Points

  • Before 2000/2001, unpaid volunteers contributed much of the work on open source software projects (the employees of companies are often contributors today).


  • Open source projects are often distributed under the General Public License (GPL); code developed under this license may not be used in commercial software, so the GPL is considered very restrictive.


  • The Berkeley Software Distribution (BSD) license, another open source license, is less restrictive, as code developed under the BSD may be used in commercial software.


  • The authors find that the output per contributor is much higher for BSD code than for GPL code, probably because there are many more contributors to GPL projects.


  • A developer may be listed as a contributor to a GPL project by contributing only a few lines of code, this suggesting that status or ideological signaling is a common motive for contributions to GPL software.

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