John Seigenthaler criticised Wikipedia's reliability
The free online resource Wikipedia is about as accurate on science as the Encyclopedia Britannica, a study shows.
The British journal Nature examined a range of scientific entries on both works of reference and found few differences in accuracy.
Wikipedia is produced by volunteers, who add entries and edit any page.
But it has been criticised for the correctness of entries, most recently over the biography of prominent US journalist John Seigenthaler.
Wikipedia was founded in 2001 and has since grown to more than 1.8 million articles in 200 languages. Some 800,000 entries are in English.
It is based on wikis, open-source software which lets anyone fiddle with a webpage, anyone reading a subject entry can disagree, edit, add, delete, or replace the entry.
It relies on 13,000 volunteer contributors, many of whom are experts in a particular field, to edit previously submitted articles.
In order to test its reliability, Nature conducted a peer review of scientific entries on Wikipedia and the well-established Encyclopedia Britannica.
The reviewers were asked to check for errors, but were not told about the source of the information.
"Only eight serious errors, such as misinterpretations of important concepts, were detected in the pairs of articles reviewed, four from each encyclopedia," reported Nature.
"But reviewers also found many factual errors, omissions or misleading statements: 162 and 123 in Wikipedia and Britannica, respectively."
Wikipedia founder Jimmy Wales welcomed the study.
"We're hoping it will focus people's attention on the overall level of our work, which is pretty good," he said.
Nature said its reviewers found that Wikipedia entries were often poorly structured and confused.
The Encyclopedia Britannica declined to comment directly on the findings; but a spokesman highlighted the quality of the entries on the free resource.
"But it is not the case that errors creep in on an occasional basis or that a couple of articles are poorly written," Tom Panelas, director of corporate communications is quoted as saying in Nature.
"There are lots of articles in that condition. They need a good editor."
Wikipedia came under fire earlier this month from prominent US journalist John Seigenthaler.
The founding editorial director of USA Today attacked a Wikipedia entry that incorrectly named him as a suspect in the assassinations of president John F Kennedy and his brother, Robert.
The false information was the work of Tennessean Brian Chase, who said he was trying to trick a co-worker.
Wikipedia has responded to the criticisms by tightening up procedures.
Next month it plans to begin testing a new mechanism for reviewing the accuracy of its articles.