Trying to Understand the Methodology of “Left Turn”

As a welcome to our guest-blogger Tim Groseclose, I’m hoping he won’t mind my effort to try to understand the methodology of the study behind his book Left Turn. As I understand the methodology, the main idea is to compare citations to think tanks by two groups, politicians and journalists. The study begins by looking at what think tanks politicians cite as authority, and uses that to get a sense of the ideology of different think tanks. It then looks at what think tanks are cited as authority by journalists at different media sources. A newspaper or TV channel is liberal if it tends to cite think tanks that are cited by liberal politicians — liberal as judged by their votes in a series of chosen legislative matters — and it’s conservative if it tends to cite think tanks that are cited by conservative politicians. So the basic conclusion of the book, that the media has a liberal bias, is rooted in the finding that most journalists cite more liberal think tank and fewer conservative think tanks than does a centrist politician. Put another way, the media is biased because when it looks for experts to quote as authority, it tends to favor liberal experts over conservative experts more than does a centrist politician.

Am I right about that, or even close? Sorry to ask such a basic question, but I don’t feel I can comment on Groseclose’s argument before I understand the methodology of the study he conducted.