PageRank, Wikipedia, and Google
http://www.marketingpilgrim.com/2007/01/campaign-to-reduce-wikipedias-pagerank-to-zero.html
The advent of Wikipedia–consistently ranked one of the top 10 most popular websites–marked a powerful transformation in the way that people access information. Content on Wikipedia can be created and/or edited by anyone with Internet access. This might allow for some biases to sneak into an article every now and again, but on the other hand it means that the collective voice of Wikipedia’s readership can correct for such biases and create a genuinely balanced product. Traditional encyclopedias, on the other hand, are subject not only to the blunders of their few editors but also to the corporate interests of their owners. Wikipedia, in other words, is truly a network of information created by the people, for the people–an emblem of democracy and the American tradition.
As anyone who has ever used an Internet search engine knows, Wikipedia pages are usually located towards the top of the results’ page. What explains Wikipedia’s ubiquitous presence–specifically, for simplicity’s sake, on Google?
One primary variable in Google’s search engine function is a given website’s PageRank. Wikipedia has an especially high PageRank, since so many of its articles are linked to by other unrelated websites. That said, it would seem that Wikipedia must help increase many other website’s PageRank, as Wikipedia articles include links to their sources (at the bottom of each page). As of 2006, however, this is untrue; Wikipedia articles includes “nofollow” values in the website URLs they cite in order to prevent these links from counting toward those websites’ PageRank values, what technology experts call “spamdexing.” This is a highly contentious tactic, however, and it has triggered a grassroots campaign in which some bloggers are using “nofollow” values when citing Wikipedia URLs in their postings in order to reduce Wikipedia’s PageRank value.
PageRank alone cannot fully explain Wikipedia’s nearly constant presence at the top of the search results’ page, and indeed Google has acknowledged the existence of a number of “secret” variables in addition to PageRank. Consider, for example, that the PageRank of a website citing Wikipedia influences Wikipedia’s PageRank; high-value websites linking to Wikipedia give Wikipedia a higher PageRank value than would low-value websites. Wikipedia is not considered a highly reputable source in the academic community and on other websites (e.g., government) that are considered authority hubs with high PageRank values. I would guess that most links to Wikipedia are from blogs and other low-PageRank value sites. This would therefore negatively influence Wikipedia’s PageRank.