According to a study by journal Nature, Wikipedia (mistakes) — such as this week's one on President Kennedy's assassination — are "the exception rather than the rule", and the resource is almost as accurate as the online Encyclopaedia Britannica, at least when it comes to science.Online encyclopedias put to the test - The Age (Australia)
Nature took stories from Wikipedia and Britannica on 42 science-related topics and submitted them to experts for review. The experts were not told which encyclopedia the stories were from. "The exercise revealed numerous errors in both encyclopedias, but among 42 entries tested, the difference in accuracy was not great: the average science entry in Wikipedia contained around four inaccuracies; Britannica, around three," according to Nature.
Congratulations, Britannica! Your professional, expert writers and editors are only 75% as inaccurate as anonymous, random, self-selected amateurs from all over.
The standard warnings against using Wikipedia as a single source for information are, and remain, pertinent, but they are but a subset of the general rule: never use *any* single source and trust it to be definitive, even when it's a venerable brand name like "Britannica."