Measuring News Slant

In Framing Bias: Media in the Distribution of Power, Robert Entman tries to re-conceptualize media effects within the context of bias. Drawing from the literatures on media framing, priming, and agenda setting, Entman theorizes about the role of news slant, or bias, in the struggle for political power within the mainstream media.

One useful contribution that Entman makes is distinguishing between three types of media bias:

• Distortion bias: News that distorts or falsifies reality
• Content bias: News that favours one side
• Decision-making bias: News twisted to serve the motivations of impartial journalists

Unlike the field of agnotology, which interests itself in the first kind of bias (among others), Entman suggests focusing on only the next two if we are to formalize a concept of media bias.

He offers the following equation:

NS = the slant of a news item
F = the perceived facts
SWH = the skill of White House news managers
SO = the skill of opposition news managers
BE = decision biases arising from evaluation of the political game
BM = decision biases arising from market competition
BI = decision biases arising from personal ideology
E = event context and other sources of variation

This equation demonstrates the complex interaction of decision biases with other factors such as the skill of a political administration's news managers.

Entman also suggests applying the Hirschman-Herfindahl index (HHI) used in economics to media slant. The HHI represents the relative power of a firm with the square of its market share percentage. Thus if one firm holds a monopoly over the market, its HHI score is 10,000 (100 x 100), but if the power is divided up among a huge number of equal competitors, their individual scores near 0. Through content analysis, something like the HHI could be applied to the media to determine aggregate slant.