In Media Bias in Presidential Election Coverage 1948-2008, Dave D'Alessio employs meta-analytic techniques to examine whether there are partisan biases in coverage of Presidential election campaigns in newspapers, on TV, and in the news magazines. This study further analyses the four essential natures of news media: as journalistic entities, property, businesses, and political actors. Aggregating the results of 99 previous studies, D'Alessio scrutinizes bias claims in news media, and why political candidates consistently make such accusations.