In yesterday's post, I noted a number of opportunities for research on the economics of social media. At least one of those opportunities intersected with the impact of traditional media. So, I was interested to read this new article by Elliott Ash, Sergio Galletta, Matteo Pinna (all ETH Zurich), and Christopher Warshaw (George Washington University), published in the Journal of Public Economics (open access). They look at the impact of Fox News Channel on political ideology of voters, and voting outcomes in the US. Given the well-known right-wing nature of Fox News, it is reasonable to wonder whether it is having a political impact.
Identifying the causal impact of a television channel is somewhat challenging, because where viewership is higher that might be because there are more right-leaning voters. So, the causality might run from voters to viewership, rather than the other way around (reverse causality). However, Ash et al. make use of the fact that the channel number assigned to Fox News varies across markets, and that assignment is random (or, at least, it isn't related to the partisanship of the population in a particular television market). So, Ash et al. use channel position as an instrument for viewership (I'll come back to this point later). They then look at the political preferences of voters using data from:
...the 2000 and 2004 National Annenberg Election Survey (NAES) and the 2006–2020 Cooperative Congressional Election Study (CCES) surveys. Overall, we have data on the preferences of approximately 661,000 Americans.
They also look at the effect on presidential and down-ballot (senate, gubernatorial, and house) elections using a variety of election data sources. They find that:
...from 2006–2008 onwards, a lower Fox News Channel (FNC) position correlates with an increase in self-identified Republican viewers, significant at the 10% level initially and 5% in recent years. A one-standard-deviation drop in FNC’s channel position corresponds to a roughly one-percentage point rise in Republican self-identification... A one-standard-deviation decrease in FNC’s channel leads the average American’s ideological position to shift .03-.04 standard deviations to the right in recent years...
Looking across time, the results are not statistically significant (at the 5 percent level) until 2009-2012, or later, depending on the measure. Turning to presidential elections, Ash et al. find that:
Initially, in the 2000 and 2004 elections, FNC’s impact was minimal, likely due to its growing viewership. By 2008, a one-standard-deviation decrease in FNC’s channel position correlated with a 0.32 increase in the Republican vote share...
And on down-ballot elections:
Overall, the effects of FNC in down-ballot elections are qualitatively similar to, though less precise than, those in presidential elections. In House elections, we see a positive (Pro-Republican) coefficient on FNC for Republicans’ two-party vote share in 2012, and it becomes statistically significant starting 2018. Since around 2012, counties with one-standard-deviation lower FNC’s channel position have about .6 to 1.6 percentage point greater shares in Republican vote.
In Senate elections, we find a positive coefficient starting in 2006, which becomes statistically significant starting in 2014.23 Since then, there have been relatively consistent year-to-year effects of around .6 to .73 percentage points. In other words, a one standard deviation shift in FNC’s channel position increases Republican Senate candidates’ vote share by over half a percentage point.
In gubernatorial races, FNC had a small and statistically insignificant effect until the latter half of the 2010s. In recent elections, however, the effect of FNC in gubernatorial races is similar to Senate races — with a Republican vote share about .5 percentage points higher...
So, it is clear from the results that Fox News Channel is driving a rightward shift in the voting public, and this is having a clear effect on both presidential and down-ballot elections. Ash et al. conclude that:
Given the estimated effect sizes on presidential elections, for example, Fox News could have easily tipped the scales for Donald Trump in 2016.
Perhaps Donald Trump should think himself lucky that his 2022 feud with Fox News didn't escalate too much?
However, there is some reason for scepticism about these results. Although Ash et al. make a good case for their use of channel position as an instrument for viewership, it turns out that they didn't actually run a full instrumental variables analysis:
Ideally, we would provide first-stage and two-stage least-squares (2SLS) results for all years in our analysis. However, there are limitations in estimating and interpreting the 2SLS results. First, we only have data on both the endogenous regressor (FNC ratings) and channel positions for 2005, 2006, 2008, and 2020. Second, the first stage provides evidence that the typical variation induced by the channel positioning is somewhat limited, suggesting that the size of the 2SLS coefficients would be, by construction, unreasonable.
...our main analysis focuses on the reduced form, where the outcomes (e.g., vote shares) are regressed directly on the instrument (FNC channel position)...
So, while they have a good instrument, a lack of data prevents them from making the most of it. And so, I think we would need further evidence before we can conclude that these results demonstrate a causal effect of Fox News Channel on political outcomes in the US. It seems to me that the main holdup to doing a full instrumental variables analysis is not having all the viewership data from Nielsen. So perhaps some wealthy research institution needs to buy that data?
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