Computer Science and Engineering, Department of


Date of this Version

Summer 8-2-2013

Document Type



A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Computer Science, Under the Supervision of Professor Anita Sarma. Lincoln, Nebraska: June, 2013

Copyright (c) 2013 Corey Jergensen


Software projects are no longer developed as individual, monolithic projects. In- stead, they exist as part of an ecosystem where related projects are developed together using a common underlying technical infrastructure and common project cultures.

This work explores characteristics of online software communities by comparing and contrasting two software ecosystems that are both related to programming, but provide different functions. The first is Stack Overflow, a programming question and answer forum. The second is Gnome, an open-source, Linux desktop environment. Both are examples of online communities because: (1) the communities are composed of smaller projects or topics, (2) users contributions are provided almost entirely by volunteers, and (3) they are managed by their members.

In this work, we investigate various aspects of each community. We start by observing how users join each community. We find that the shared infrastructure of the Gnome ecosystem allows users to join additional projects within the community at an accelerated rate. In Stack Overflow, we find there are a higher number of users attempting to contribute than typically observed in other online communities. We observe that the reduction in the overhead in joining communities leads to a higher number of contributions being provided by a larger base of users.

We then study the distribution of contributions amongst members in each com- munity. We find that each community has a skewed distribution of contribution with a small minority providing more content than the remainder of the community. In

Stack Overflow however, we observe that the high and low contribution groups of users provide a similar amount of contribution, a finding different from what has been observed in other communities.

Last, we look at the role experienced users fill in the community. In Gnome, tenured users contribute less code and may spend an increased amount of time on community and project management. In Stack Overflow, tenured users may perform moderator tasks that help the community function and provide feedback on the site’s operation. In each community, tenured users show a vested interest in the community and its continued success.

Advisor: Anita Sarma