Paying the piper: government advertising and media bias

In many countries around the world, governments cannot exercise outright censorship, so they need to resort to more subtle or sophisticated instruments to try to influence the media. We use sentiment analysis to measure the tone of opinion columns in all major Mexican newspapers and develop a method to measure how much the federal government influences such tone through its expenditure in publicity. The evidence is clear: more expenditure is associated with a favourable tone towards the government and a harsher tone towards the opposition. Furthermore, we validate our quantitative findings with qualitative evidence from a case study for which we also have extensive data on opinion tone and government spending.

Printed media can shape its audience’s political preferences. Research on governments influencing their narrative focuses on censorship of political scandals but largely ignores day-to-day political content. We analyze opinion columns from Mexico, a country with a democratic culture where outright censorship is unfeasible, and yet there is journalistic evidence on the government “sponsoring” the media to communicate messages with a less negative tone. We estimate the negative tone of over 200,000 opinion pieces from Mexico’s eight most prominent newspapers using sentiment analysis. We propose a novel metric of media capture that conveys the over-favoring of publicity spending by the government in news outlets. We find that captured media are less negative about the incumbent president and more negative about their main political rival, suggesting media organizations adapt their content to their advertisers’ preferences. The results are validated by rare qualitative evidence that uncovers the blacklisting of media deemed too negative of the incumbent.