Most of the textual analysis of wikis has been directed at Wikipedia, with much of the research focus on its accuracy. Its breadth of content, ease of access, free cost, and links to external material make Wikipedia potentially highly useful to a vast online audience. The foremost question for casual users and researchers alike has been whether the collaborative process that welcomes the participation of novices as well as experts can produce satisfactorily accurate results. In a widely cited study on this topic,Nature (Giles, 2005) had a panel of experts compare content from 42 entries of approximately the same length on scientific topics from Wikipedia and the Encyclopaedia Britannica. The experts identified 162 errors in the Wikipedia content (four of which were serious) and 123 in the Encyclopaedia Britannica content (four of which were serious), thus suggesting that neither encyclopedia is infallible and that the six-year-old open source Wikipedia is only slightly less accurate than the 238-year-old professionally edited Britannica. In a related study, Chesney (2006) had 258 research staff judge the credibility of two Wikipedia articles, one in their area of expertise and one chosen randomly. In general, the researchers found the articles to be credible, and even more so in their own area of expertise.