German magazine Stern has tested the German language version of Wikipedia against the online version (for subscribers) of the encyclopedia Brockhaus. 50 random words were picked from a range of topics and a professional research agency evaluated the entries. Wikipedia came out on top in no less than 43 of the 50 words.
The whole 13-page (!) article is not online, but Wikipedistik (in German) has more details. The criteria were: accuracy (weight 40 percent), completeness (30), topicality/up to date (20), intelligibility/easy to understand (10). Out of this notes were constructed, and Wikipedia received on average 1,7, Brockhaus 2,7 (on a scale from 1 to 6 where 1 is best). (via the Wikimedia fundraising blog).
UPDATE after reading the whole article:
The only criteria where Brockhaus became a better note was for “Verständlichkeit” — i.e. how easy the text is to understand. That is of course a structural problem for Wikipedia that has been noted by many. Articles tend to suffer from a lack of editing. They are often too long, some aspects are described in too much detail, there is no real narrative flow. Theoretically this should improve over time. If it really is true that Wikipedia will run out of new topics, contributors could spend time on improving editing, adding references etc to existing articles. However, the big encouragement that (German) Wikipedians must bring with them from this test is that their articles got the excellent note 1,6 on accuracy (Brockhaus: 2,3). That really is impressive.
