John Seigenthaler criticised Wikipedia's reliability
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.
Open approach
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.
We're very pleased with the results and we're hoping it will focus people's attention on the overall level of our work, which is pretty good
Jimmy Wales, Wikipedia founder
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.
Writing style
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.
Wikipedia logo
An investigation performed by the scientific review, ''Nature'', on Wikipedia and Britannica science entries, found that the two encyclopedias have similar degrees of accuracy in their content. 

''Nature'' used peer reviewing to compare Wikipedia and Britannica's coverage of science. In this study, entries were chosen from the websites of Wikipedia and Encyclopaedia Britannica on a broad range of scientific disciplines and sent to a relevant expert for peer review. Each reviewer examined the entry on a single subject from the two encyclopedias without being told which article came from which encyclopaedia. The reviewers were asked to check for errors, but were not told where the information came from.

Among 42 entries tested, the difference in accuracy was not significant: the average science entry in Wikipedia contained around four inaccuracies; Britannica, about three. In the pairs of articles reviewed, eight serious errors such as misinterpretations of important concepts were detected, four from each encyclopaedia. Reviewers also found many factual errors, omissions or misleading statements: 162 in Wikipedia and 123 in Britannica.  Additionally, it was found that Wikipedia articles are 2.6 times as long as Britannica articles, meaning that there is a lower error/ommision per word ratio in Wikipedia.

The main criticism about Wikipedia was on its readability, with several reviewers commenting that the articles they read were poorly structured and confusing. 

As well as comparing the two encyclopedias, ''Nature'' surveyed more than 1,000 Nature authors and found that although more than 70% had heard of Wikipedia and 17% of those consulted it on a weekly basis, less than 10% help to update it. 

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 told BBC News.