Payment of OS Developers

Does Payment of the Programmers Endanger the Principles of Open Source Software Development?

URL = http://wy2x05.psychologie.uni-wuerzburg.de/ao/research/oss_development.php

"Goals of the study

We are interested in the reasons why software developers (such as you) are willing to work in Open Source projects, and we would like to compare these motives with those of software developers in commercial or 'closed' software projects. Particularly we are interested if, and in what respect, motivations to contribute changes when software developers are paid for their work."