Since its inception six years ago, the online encyclopedia Wikipedia has accumulated 6.40 million articles and 250 million edits, contributed in a predominantly undirected and haphazard fashion by 5.77 million unvetted volunteers. Despite the apparent lack of order, the 50 million edits by 4.8 million contributors to the 1.5 million articles in the English–language Wikipedia follow strong certain overall regularities. We show that the accretion of edits to an article is described by a simple stochastic mechanism, resulting in a heavy tail of highly visible articles with a large number of edits. We also demonstrate a crucial correlation between article quality and number of edits, which validates Wikipedia as a successful collaborative effort.

This paper analyzes which pages and topics are the most popular on Wikipedia and why. For the period of September 2006 to January 2007, the 100 most visited Wikipedia pages in a month are identified and categorized in terms of the major topics of interest. The observed topics are compared with search behavior on the Web. Search queries, which are identical to the titles of the most popular Wikipedia pages, are submitted to major search engines and the positions of popular Wikipedia pages in the top 10 search results are determined. The presented data helps to explain how search engines, and Google in particular, fuel the growth and shape what is popular on Wikipedia.

This study demonstrates among a sample of 100 Wikipedia entries, which included 168 sources or references, only two percent of the entries provided links to open access research and scholarship. However, it proved possible to locate, using Google Scholar and other search engines, relevant examples of open access work for 60 percent of a sub-set of 20 Wikipedia entries. The results suggest that much more can be done to enrich and enhance this encyclopedia’s representation of the current state of knowledge. To assist in this process, the study provides a guide to help Wikipedia contributors locate and utilize open access research and scholarship in creating and editing encyclopedia entries.

People often implicitly ascribe the quality of peer–production projects such as Project Gutenberg or Wikipedia to what I call “laws” of quality. These are drawn from Open Source software development and it is not clear how applicable they are outside the realm of software. I look at examples from peer production projects to ask whether faith in these laws does not so much guarantee quality as hide the need for improvement.