It’s hard to measure media bias in general because bias is hard to quantify.  Movie reviews are one way forward, a cool idea in a new paper by DellaVigna and Kennedy.  Here’s the abstract:

Fueled by the need to cut costs in a competitive industry, media companies have be- come increasingly concentrated. But is this consolidation without costs for the quality of information? Concentrated media companies generate a conflict of interest: a media outlet can bias its coverage to benefit companies in the same group. We test empirically for bias by examining movie reviews by media outlets owned by News Corp.–such as the Wall Street Journal–and by Time Warner–such as Time. We find a statistically significant, if small, bias in the review score for 20th Century Fox movies in the News Corp. outlets. We detect no bias for Warner Bros. movies in the reviews of the Time Warner outlets, but find instead some evidence of bias by omission: the media in this group are more likely to review highly-rated movies by affiliated studios. Using the wealth of detail in the data, we present evidence regarding bias by individual reviewer, and also biases in the editorial assignment of review tasks. We conclude that reputation limits the extent of bias due to conflict of interest, but that nonetheless powerful biasing forces are at work due to consolidation in the media industry.

Tubeteika toss:  Josh Gans.

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