Is Wikipedia Bias?

Astonishing information:

As the largest wiki ever and one of the most popular websites in the world, Wikipedia accommodates a skyrocketing number of contributors and readers. At the end of 2011, after approxi- mately a decade of production, Wikipedia sup- ports 3.8 million articles in English and well over twenty million articles in all languages, and it produces and hosts content that four hun- dreds of millions of readers view each month. Every ranking places Wikipedia as the fifth or sixth most visited website in the United States, behind Google, Facebook, Yahoo!, YouTube, and, perhaps, eBay. In most countries with unrestricted and developed Internet sectors, Wikipedia ranks among the top ten websites vis- ited by households. 

This achievement is astonishing in light of the resources deployed. Wikipedia achieved its size and high profile with minimal staff. Wikipedia is part of a not-for-profit organization. Donations entirely fund the operations. The vast majority of its content comes from volunteer contribu- tors, who sew contributions together with edit- ing and prose.

The authors say:

Wikipedia’s editors and contributors aspire to generate articles with an NPOV ["Neutral Point of View"]. While that goal faces fewer challenges when the information is objective and easily verified, and the topic is uncontroversial, this study examined settings where such conditions are less likely to hold. The study examined a decade of slant in articles about US politics, where some of the articles cover controversial topics, and include inher- ently subjective and unverifiable information. 

The findings show that many of these articles contain bias, and both the level and direction of bias evolves over time. To summarize, the average old political article in Wikipedia leans Democratic. Gradually, Wikipedia’s articles have lost that disproportionate use of Democratic phrases, moving to nearly equivalent use of words from both parties, akin to an NPOV on average. The number of recent articles far outweighs the number of older articles, so, by the last date, Wikipedia’s articles appear to be centered close to a middle point on average.

Source: Greenstein and Zhu (American Economic Review: Papers & Proceedings, 2012).

See also a recent open letter to Wikipedia.