A landmark 2005 study published in Nature compared 42 science articles from Wikipedia and Encyclopaedia Britannica. The study found that Wikipedia had 162 total errors, averaging four per article, while Britannica had 123 errors, averaging three per article. Both had the same number of serious errors, but Wikipedia had more overall mistakes.
Subsequent discussions, including sources like CNET and The Guardian, have cited this study as the most rigorous head-to-head comparison. Britannica disputed the methodology, but no newer comprehensive study has overturned these findings or shown Wikipedia to be more accurate.
While Wikipedia has expanded significantly since 2005, there is no evidence from updated direct comparisons showing it has surpassed Britannica in accuracy. Both sources continue to be widely used, but Britannica maintains a stronger record for editorial oversight.