Measuring Wikipedia

Wikipedia, an international project that uses Wiki software to collaboratively create an encyclopaedia, is becoming more and more popular. Everyone can directly edit articles and every edit is recorded. The version history of all articles is freely available and allows a multitude of examinations. This paper gives an overview on Wikipedia research. Wikipedia’s fundamental components, i.e. articles, authors, edits, and links, as well as content and quality are analysed. Possibilities of research are explored including examples and first results. Several characteristics that are found in Wikipedia, such as exponential growth and scale-free networks are already known in other context. However the Wiki architecture also possesses some intrinsic specialities. General trends are measured that are typical for all Wikipedias but vary between languages in detail. Introduction Wikipedia is an international online project which attempts to create a free encyclopaedia in multiple languages. Using Wiki software, thousand of volunteers have collaboratively and successfully edited articles. Within three years, the world’s largest Open Content project has achieved more than 1.500. 000 articles, outnumbering all other encyclopaedias. Still there is little research about the project or on Wikis at all. Most reflection on Wikipedia is raised within the community of its contributors. This paper gives a first overview and outlook on Wikipedia research. Wikipedia is particularly interesting to cybermetric research because of the richness of phenomena and because its data is fully accessible. One can analyse a wide variety of topics that range from author collaboration to the structure and growth of information with little effort for data collection and with high comparability. A short history of Wikipedia Wikipedia is one of the largest instances of a Wiki and one of the 100 most popular Websites worldwide. It uses Wiki software, a type of collaborative software that was invented first by Ward Cunningham in 1995 (Cunningham & Leuf, 2001). He created a simple tool for knowledge management and decided to name it WikiWikiWeb using the Hawaiian term “wiki” for “quick” and with allusion to the WWW. Briefly a Wiki is a collection of hypertext documents that can directly be edited by anyone. Every edit is recorded and thus can be retraced by any other user. Each version of a document is available in its revision history and can be compared to other versions. Wikipedia originated from the Nupedia project. Nupedia was founded by Jimmy Wales who wanted to create an online encyclopaedia licensed under the GNU Free Documentation License. In January 2001 Wikipedia was started as a side project to allow collaboration on articles prior to entering the lengthy peer review process. Soon it grew faster and attracted more authors than Nupedia which was closed in 2002. In addition to the original English Wikipedia Wikipedias in other languages soon were launched. In March 2005 there are 195 registered languages, 60 languages have more than 1.000 and 21 languages more than 10.000 articles. The English Wikipedia is the largest one, followed by German, Japanese and French. In June 2003 the Wikimedia Foundation was founded as an independent institution. It is aimed at developing and maintaining open content, Wiki-based projects and to provide the full contents of these projects to the public free of charge. Meanwhile Wikimedia hosts also Wiki projects to create dictionaries, textbooks, quotes, media etc. In 2004 a German nonprofit association was founded to assist the project locally. Associations in other countries follow. Their main goals are collecting donations, promotion of Wikipedia and social activities within the 1 See http://de.wikipedia. org/wiki/Wikipedia:Wikipedistik/Bibliographie (retrieved April 10, 2005) on Wikipedia and http://www.public. iastate.edu/~CYBERSTACKS/WikiBib.htm (January 30, 2005) on Wikis. 2 http://www.alexa. com/data/details/traffic_details? y=t&url=Wikipedia.org, retrieved April 7, 2005