In 2008, researchers at Carnegie Mellon University found that the quality of a Wikipedia article would suffer rather than gain from ding more writers when the article lacked appropriate explicit or implicit coordination. For instance, when contributors rewrite small portions of an entry rather than making full-length revisions, high- and low-quality content may be intermingled within an entry. Roy Rosenzweig, a history professor, stated that American National Biography Online outpered Wikipedia in terms of its "clear and engaging prose", which, he said, was an important aspect of good historical writing. Contrasting Wikipedia's treatment of Abraham Lincoln to that of Civil War historian James McPherson in American National Biography Online, he said that both were essentially accurate and covered the major episodes in Lincoln's , but praised "McPherson's richer contextual ization ... his artful use of quotations to capture Lincoln's voice ... and ... his ability to convey a profound message in a handful of words." By contrast, he gives an example of Wikipedia's prose that he finds "both verbose and dull". Rosenzweig also criticized the "waffling—encouraged by the NPOV policy— means that it is hard to discern any overall interpretive stance in Wikipedia history". While generally praising the article on William Clarke Quantrill, he d its conclusion as an example of such "waffling", which then stated: "Some historians ... re him as an opportunistic, bloodthirsty outlaw, while others continue to view him as a daring soldier and local folk hero." Other critics have me similar charges that, even if Wikipedia articles are factually accurate, they are often written in a poor, almost unreable style. Frequent Wikipedia critic Andrew Orlowski commented, "Even when a Wikipedia entry is 100 per cent factually correct, and those facts have been carefully chosen, it all too often res as if it has been translated from one language to another then into a third, passing an illiterate translator at each stage." A study of Wikipedia articles on cancer was conducted in 2010 by Yaacov Lawrence of the Kimmel Cancer Center at Thomas Jefferson University. The study was limited to those articles that could be found in the Physician Data Query and excluded those written at the "start" class or "stub" class level. Lawrence found the articles accurate but not very reable, and thought that "Wikipedia's lack of reability (to non-college reers) may reflect its varied origins and haphazard editing". The Economist argued that better-written articles tend to be more reliable: "inelegant or ranting prose usually reflects muddled thoughts and incomplete ination". These numbers refer to the number of articles: it is possible for one topic to contain a large number of short articles and another to contain a small number of large ones. Through its "Wikipedia Loves Libraries" program, Wikipedia has partnered with major public libraries such as the New York Public Library for the Pering Arts to expand its coverage of underrepresented subjects and articles. A 2011 study conducted by researchers at the University of Minnesota indicated that male and female editors focus on different coverage topics. T was a greater concentration of females in the "people and arts" category, while males focus more on "geography and science". Coverage of topics and selection bias Research conducted by Mark Graham of the Oxford Internet Institute in 2009 indicated that the geographic distribution of article topics is highly uneven. Africa is the most underrepresented. Across 30 language editions of Wikipedia, historical articles and sections are generally Eurocentric and focused on recent events.