Remarks on Groseclose’s Left Turn

In his recent book Left Turn, Tim Groseclose concludes that, in a world without media bias, the average American voter would be positioned at around 25 on a 0–100 scale, where 0 is a right-wing Republican and 100 is a left-wing Democrat. In this world, a balanced media might include some TV networks promoting the view that abortion should be illegal under all circumstances and subject to criminal penalties, whereas others might merely hold that Roe v. Wade is unconstitutional; some media outlets might support outright discrimination against gays whereas others might be neutral on civil unions but oppose gay marriage; and on general politics there might be some newspapers that endorse hard-right Republican candidates (0 on Groseclose’s 0–100 scale) whereas those on the left would endorse positions near those currently held by Senator Olympia Snowe. But instead of this, Groseclose must endure a world where he estimates the average voter is around 50, with all that follows from this, and he attributes this difference to media bias. Groseclose sets up this stirring climax by formulating and estimating three models. The first model, from Groseclose and Milyo [2005], is an ideal-point model that puts media organizations and members of Congress on that 100 point scale, based on how often they refer to various research and advocacy organizations. The second infers the political positions of voters in different districts based on how many of them voted for Obama, and the estimated positions of their members of Congress. The third model, new to Left Turn, is a causal model of how media influence the positions of voters. Groseclose’s claims about what our country would look like if it weren’t for media bias thus rest on a multi-stage analysis. (Figure 1 depicts his estimation strategy.) He estimates latent quantities, such as how Americans would vote if their views were not distorted by the media, in terms of other latent, estimated quantities, such as the political location of media organizations.