Contributing to public document repositories: a critical mass theory perspective

Public document repositories (PDRs) are valuable resources available on the Internet and are a component of the broader information commons freely accessible to the public. Instances of PDRs include the repository of reviews at Amazon.com and the online encyclopedia at Wikipedia. These repositories are created and sustained by the voluntary contributions of individuals who are not compensated for their inputs. This paper draws on and extends critical mass theory in the context of PDRs. Using data on the reviews written by prolific reviewers at Amazon.com and the text of their personal profiles, we find the critical mass of contributors at the PDR not only to be prolific and contributing high-quality reviews, but also to be among the earliest contributors of reviews on products. Reviewer profiles revealed the presence of multiple self-oriented motives (self expression, personal development, utilitarian motives, and enjoyment) and other-oriented motives (social affiliation, altruism, and reciprocity) for contribution. We find that the quality and quantity of contributions are inversely related and the motives for quantity of contribution are different from those related to the quality of contribution. The study highlights that PDRs are viewed by contributors as social contexts even though making contributions is an individual act that does not involve social interaction.