  This paper aims to review the fiercely discussed question of whether the
ranking of Wikipedia articles in search engines is justified by the quality of
the articles. After an overview of current research on information quality in
Wikipedia, a summary of the extended discussion on the quality of encyclopedic
entries in general is given. On this basis, a heuristic method for evaluating
Wikipedia entries is developed and applied to Wikipedia articles that scored
highly in a search engine retrieval effectiveness test and compared with the
relevance judgment of jurors. In all search engines tested, Wikipedia results
are unanimously judged better by the jurors than other results on the
corresponding results position. Relevance judgments often roughly correspond
with the results from the heuristic evaluation. Cases in which high relevance
judgments are not in accordance with the comparatively low score from the
heuristic evaluation are interpreted as an indicator of a high degree of trust
in Wikipedia. One of the systemic shortcomings of Wikipedia lies in its
necessarily incoherent user model. A further tuning of the suggested criteria
catalogue, for instance the different weighing of the supplied criteria, could
serve as a starting point for a user model differentiated evaluation of
Wikipedia articles. Approved methods of quality evaluation of reference works
are applied to Wikipedia articles and integrated with the question of search
engine evaluation.
