2018 Midterms: Did anti-establishment Democrats perform better?

Republicans here!

Anti-establishment Democrats outperformed establishment Democrats by an average of 1.9 points relative to their districts’ partisan leans in the 2018 U.S. House general elections

However…

• The observed effect is relatively small at just 1.9 percentage points. 8.2 point overperformance for anti-establishment candidates (n = 60) compared to 6.3 point overperformance for establishment candidates (n = 149). Both groups significantly overperformed their districts’ partisan leans.

• The effect is barely statistically significant (p = 0.049).

• A lot depends on how one defines “anti-establishment”. Several fields in the dataset were used to categorize a candidate as “anti-establishment” or not:

  • Yes on any of the following fields indicated the candidate was anti-establishment: Warren Endorsed?, Sanders Endorsed?, Our Revolution Endorsed?, Justice Dems Endorsed?, PCCC Endorsed?, Indivisible Endorsed?, WFP Endorsed?
  • No on any of the following fields indicated the candidate was anti-establishment: Biden Endorsed?, No Labels Support?
  • The following fields were not considered indicative of establishment/anti-establishment status:
    • Party Support? - Political parties often throw their support behind viable candidates in competitive races (in general elections), even if the candidates don’t line up completely with the party establishment.
    • Obama Alum? - Originally, I had thought that a candidate who previously worked in the former president’s administration couldn’t possibly be considered anti-establishment, but after some research, I concluded that having served in an administration does not mean one is ideologically aligned with said administration.

What if?

If Biden Endorsed? were ignored, and/or Party Support? and/or Obama Alum? were considered indicative of establishment status, the observed effect becomes even smaller (closer to 1 point) and the effect is no longer statistically significant. This illustrates that the effect is very small and highly dependent on how one categorizes a candidate as “establishment” or “anti-establishment”.

Notes

I used FiveThirtyEight’s dataset on 2018 Democratic primary candidates. This dataset includes only candidates who had primary challengers, so incumbent U.S. Representatives who did not face a primary challenge were excluded from this analysis.

Data Sources

2018 Midterms

2018 Midterms: Did anti-establishment candidates really perform better?

“The Year of the Woman”: Did candidate gender impact electoral performance?

2018 Midterms: Did candidates’ professional background, characteristics, and/or identities affect performance?

U.S. House: Do moderates come from swing districts? Relationship between caucus/coalition membership and district partisan lean

Last Updated: Feb 8, 2019