Comments on "There is no liberal media bias in which news stories political journalists choose to cover"
1.
The Hassell et al. 2020 Science Advances article "There is no liberal media bias in which news stories political journalists choose to cover" reports null results from two experiments on ideological bias in media coverage.
The correspondence experiment emailed journalists a message about a candidate who planned to announce a candidacy for state legislator, with a question of whether the journalist would be interested in a sit-down interview with the candidate to discuss the candidate's candidacy and vision for state government. Experimental manipulations involved the description of the candidate, such as "...is a true conservative Republican..." or "...is a true progressive Democrat...".
The conjoint experiment asked journalists to hypothetically choose between two candidacy announcements to cover, with characteristics of the candidates experimentally manipulated.
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2.
Hassell et al. 2020 claims that (p. 1)...
Using a unique combination of a large-scale survey of political journalists, data from journalists' Twitter networks, election returns, a large-scale correspondence experiment, and a conjoint survey experiment, we show definitively that the media exhibits no bias against conservatives (or liberals for that matter) in what news that they choose to cover.
I think that a good faith claim that research "definitively" shows no media bias against conservatives or liberals in the choice of news to cover should be based on at least one test that is very likely to detect that type of bias. But I don't think that either experiment provides such a "very likely" test.
I think that a "very likely" scenario in which ideology would cause a journalist to not report a story has at least three characteristics: [1] the story unquestionably reflects poorly on the journalist's ideology or ideological group, [2] the journalist has nontrivial gatekeeping ability over the story, and [3] the journalist could not meaningfully benefit from reporting the story.
Regarding [1], it's not clear to me that any of the candidate announcement stories would unquestionably reflect poorly on any ideology or ideological group. The lack of an ideological valence to the story is especially lacking in the correspondence experiment, given that a liberal journalist could ask softball questions to try to make a liberal candidate look good and could ask hardball questions to try to make a conservative candidate look bad.
Regarding [2], it's not clear to me that a journalist would have nontrivial gatekeeping ability over the candidate announcement story: it's not like a journalist could keep secret the candidate's candidacy.
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3.
I think that title of the Hassell et al. 2020 Monkey Cage post describing this research is defensible: "Journalists may be liberal, but this doesn't affect which candidates they choose to cover". But I'm not sure who thought otherwise.
Hassell et al. 2020 describe the concern about selective reporting as "... journalists may omit news stories that do not adhere to their own (most likely liberal) predispositions" (p. 1). But in what sense does a conservative Republican announcing a candidacy for office have anything to do with adhering to a liberal disposition? The concern about media bias in the selection of stories to cover, as I understand it, is largely about stories that have an obvious implication for ideologically preferred narratives. So something like "Conservative Republican accused of sexual assault", not "Conservative Republican runs for office".
The selective reporting that conservatives complain about is plausibly much more likely—and plausibly much more important—at the national level than at a lower level. For example, I don't think that ideological bias is large enough to cause a local newspaper to not report on a police shooting of an unarmed person in the newspaper's distribution area; however, I think that ideological bias is large enough to influence a national media organization's decisions about which subset of available police shootings to report on.