Christian Bird Adrian Bachmann Eirik Aune John Duffy Abraham Bernstein Vladimir Filkov Premkumar T. Devanbu Fair and balanced?: bias in bug-fix datasets. 121-130 2009 ESEC/SIGSOFT FSE http://doi.acm.org/10.1145/1595696.1595716 conf/sigsoft/2009 db/conf/sigsoft/fse2009.html#BirdBADBFD09