Lelkes, Y., Sood, G., & Iyengar, S. (2017). The hostile audience: The effect of access to broadband internet on partisan affect. American Journal of Political Science, 61(1), 5-20.
The main purpose of this paper is to identify the causal impact of broadband access on affective polarization by exploiting differences in broadband availability brought about by variation in state right of-way regulations (ROW), which significantly affect the cost of building Internet infrastructure and thus the price and availability of broadband access. The data on right-of-way laws come from an index of these laws. The data on broadband access are from the Federal Communication Commission (FCC). For data on partisan affect, we use the 2004 and 2008 National Annenberg Election Studies (NAES). For media data, they use comScore. Their results suggest that had all states adopted the least restrictive right-of-way regulations observed in the data, partisan animus would have been roughly 2 percentage points higher. Finally, they demonstrate that an alternative set of instruments for broadband availability (surface topography) yields very similar results.
The authors start the paper by trying to convince the readers that polarization, partisanship is increasing. For instance, they mention that partisan prejudice exceeds implicit racial prejudice  (Iyengar and Westwood 2014). I skimmed that paper and the data is publicly available on Dataverse, it’s cross-sectional. There is no actual proof of that statement, and it was not necessary. As the authors stress: “In contemporary America, the strength of these norms has made virtually any discussion of racial differences a taboo subject to the point that citizens suppress their true feelings” .
My point is, this entire “increase in polarization” depends on:
- When do we start the “counter” (the clock)?
- Establishing causal relationship between X factor(s) an “polarization” is not easy. Especially when are trying to isolate one factor: broadband internet.
In addition, the phrase “media consumption is strongly elastic, increasing sharply with better access”, should have probably stressed that it is “elastic with respect to internet speed”, which is what the authors meant. In general, people tend to associate elasticity with price, and I doubt media consumption is not “strongly elastic” with respect to price.
2. 1. Assumptions
“[..] access to broadband primarily increases the size of the pie, without having much impact on the ratio of the individual slices. Assuming patterns of consumption remain roughly the same, any increase in consumption necessarily means greater exposure to imbalanced political information.”
This is a bold assumption. I am not sure how we can assume something like that and there are no citations whatsoever to back this up. To put thing into perspective, this means “your grandfather’s generation media consumption pattern is roughly the same as yours, Millennials”
Another assumption is the following:
“Right of-way regulations (ROW), which significantly affect the cost of building Internet infrastructure and thus the price and availability of broadband access.”
While this make “sense”, there are huge theoretical leaps here. Here is why ROW (A) implies cost of infrastructure (B) but does not imply price and availability (C): cross-subsidization. Corporations can “afford” reducing the prices in specific areas to increase their market share even if the initial costs are high. This is quite common in the telecommunication and broadband services.
2.2. Technical issues
While the authors test the “strength” of the instrument in a somewhat crude way, they do not test anything else which is problematic. Specifically, I didn’t see any test anywhere regarding the validity of the instrument. There is a citation provided for a dissertation thesis that also has no test. For future reference, this is a framework on how to go forward when you decide to utilize IV/2SLS methodologies based on the Godfrey-Hutton Procedure:
- Weak Instrument Test (or strength of instrument)
- One way is to implement Godfrey’s two step method and get “Shea’s Partial R square”.
- Over-identification Test (validity test/instrument exogeneity)
- Sargan’s Overidentification Test (sometimes called J test)
- If pass step 1 and 2 proceed with a Hausman Test
- This confirms the existence of endogeneity.
- Are we now more polarized as a country than during the Vietnam War? If the answer no, what does this mean? I doubt there was broadband internet back then.
- Two assumptions that I mention in the main text.
- Patterns of consumption remain the same?
- The increase in costs does not necessarily affect the price of broadband internet.
- Technical issues, lack of a validity test which might yield biased results.