The quality of Wikipedia has been well established. A well-known study was carried out in 2005 by scientific journal Nature showing that the accuracy of Wikipedia articles on science was comparable to that of Encyclopedia Brittanica. A more recent study by Epic and University of Oxford again showed comparable quality of articles across many domains of study and languages.
These well-publicized studies have led people to believe that Wikipedia is always a reliable source of information. However the problem is that both of these studies compared articles of substance on academic topics. There are more than 23 million articles on Wikipedia, and around 130,000 on Encyclopedia Brittanica. There is no way to assess on a comparative basis the accuracy of the close to 23 million Wikipedia articles on topics that aren’t substantively covered elsewhere.