A study by Lawrence Soley in his book The News Shapers found that the US evening news broadcasts by the three major television networks tended to have a centre-right bias—using ex-government officials, conservative think tank experts and corporate consultants as analysts rather than left activists or progressive think tanks experts.
Economist Dean Baker says news stories on trade, for example, almost always rely on sources in government and business without questioning the vested interests that these sources might have in the issues. This is supported by a 1993 study, which found that “leading newspapers overwhelmingly used pro-NAFTA sources” when reporting on the North American Free Trade Agreement. This was despite the opposition to the Agreement from environmental and labour groups.
A 1989 study, conducted by media monitoring group, Fairness & Accuracy in Reporting (FAIR), of the highly regarded US ABC television current affairs show Nightline found that 80 per cent of its US guests were professionals, government officials or corporate representatives. Five percent represented public interest groups and less than two percent represented labour or ethnic groups; 89 per cent were male and 92 per cent were white. The study concluded that “Nightline serves as an electronic soapbox from which white, male, elite representatives of the status quo can present their case.” (Nightline also influences who is used as a source by other journalists.)
Even on public television experts used for economic coverage were mainly corporate representatives. For all public television coverage, 18 percent of sources were corporate representatives compared with 6 percent who were activists of all persuasions. Environmentalists made up 0.6 per cent of sources. The researchers concluded: “While there were exceptions.... public television did little to highlight the voices of organised citizens, relegating activists along with members of the general public to the margins of political discourse.”
Documentaries, although having more diversity of voices, still relied on the usual news sources. Nevertheless, the constant complaints from conservatives about the liberal bias of public broadcasting tends to exert an ongoing pressure towards conservatism.