Does Conflict of Interest Lead to Biased Coverage? Evidence from Movie Reviews*
研究媒体集团内部利益冲突是否导致报道偏向，通过对比新闻集团和时代华纳旗下媒体对关联公司电影的评分，发现没有证据支持存在系统性偏差。
Media outlets are increasingly owned by conglomerates, inducing a conflict of interest: a media outlet can bias its coverage to benefit companies in the same group. We test for bias by examining movie reviews in media outlets owned by News Corp, such as the Wall Street Journal, and Time Warner, such as Time. We find higher ratings for 20th Century Fox movies in News Corp. outlets compared to movies by other studios. To disentangle bias from correlation of taste, we introduce and validate a novel matching procedure using individual movie ratings from online platforms. Using this procedure, we find no evidence of bias in News Corp. nor Time Warner outlets. We reject even small effects, such as bias of one extra star (out of four) every thirteen movies. We test for differential bias when the return to bias is plausibly higher, examine bias by media outlet and by journalist, as well as editorial bias. We also consider bias by omission—whether media outlets are more likely to review highly-rated movies by affiliated studios—and conflict of interest within a movie aggregator. In none of these dimensions do we find evidence of bias. We relate to previous work and discuss three explanations for the lack of bias in our setting: high values of media reputation, organizational features in a conglomerate, and low returns to bias.