"The research technique used in this study hardly inspires confidence. In fact, it is logically suspect and simply baffling in some of its details.
First, its measure of media bias consists entirely of counting the number of mentions of, or quotes from, various think tanks that the researchers determine to be 'liberal' or 'conservative.' By this logic, a mention of Al Qaeda in a story suggests the newspaper endorses its views, which is obviously not the case. And if a think tank is explicitly labeled 'liberal' or 'conservative' within a story to provide context to readers, that example doesn't count at all. The researchers simply threw out such mentions.
Second, the universe of think tanks and policy groups in the study hardly covers the universe of institutions with which Wall Street Journal reporters come into contact. What are we to make of the validity of a list of important policy groups that doesn't include, say, the Chamber of Commerce, the National Association of Manufacturers, the AFL-CIO or the Concord Coalition, but that does include People for the Ethical Treatment of Animals? Moreover, the ranking the study gives to some of the groups on the list is simply bizarre. How seriously are we to take a system that ranks the American Civil Liberties Union slightly to the right of center, and that ranks the RAND Corp. as more liberal than Amnesty International? Indeed, the more frequently a media outlet quotes the ACLU in this study, the more conservative its alleged bias."