Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
This paper connects the rise in polarization to changes in media technology, which allow for higher precision in the advertising strategy of candidates. Candidates place ads in media outlets whose audiences differ in ideology and size. We develop the concept of media centrality, which takes into account differences in the media network and in ideology. Media centrality leads to a simple characterization of both the optimal targeting strategy and policy. We show that generally a more fragmented media landscape leads to an increase in polarization.