The 2016 GOP primary has had the highest number of presidential candidates running for one party’s nomination at one time. It has showcased what pundits have described as a GOP civil war between “establishment” and anti-establishment or populist wings of the party. Interestingly, the high number of candidates in the race gives us a measurement tool to better understand the underlying structure of the race and the intra-party civil war.
Put This Theory to the Test
To identify clusters of presidential candidates who have attracted similar types of voters, I analyzed data collected in a November 2015 Cato/YouGov survey on criminal justice reform and policing that included questions on the election. Although this data doesn't have the latest horserace numbers, it can still tell us about the race's underlying dynamics.
The survey asked all respondents—Democrat and Republican—if they would or would not consider voting for each of the Democratic and Republican presidential candidates. Using a variety of statistical tools, I found GOP candidates are likely competing alongtwo main dimensions in the primary: a populist/establishment dimension, and an ideological dimension. Rand Paul comes close to defining a third dimension, and stands apart from the other GOP candidates. I'll explain.
Factor analysis conducted with principal component factor extraction with oblique rotation revealed two factors with eigenvalues greater than 1. The survey included a battery of questions asking respondents if they would or would not consider voting for each of the candidates. These variables, coded as 0/1, were included in the factor analysis.
I used a statistical test  (factor analysis) of all the GOP candidate variables to examine which candidates tend to attract similar types of GOP voters. The test can also indicate if candidates are competing along one dimension (like establishment versus antiestablishment) or perhaps more. To be sure, this analysis is both an art and a science, and some subjective interpretation is necessary. The results indicate there are two statistically meaningful dimensions along which candidates are competing, but it can't identify what they are—that's up for interpretation.
Do You Value Ideology or Populism More?
As you can see in the chart, Donald Trump heads up one dimension (horizontal axis) and Ted Cruz leads the other dimension (vertical axis), while Jeb Bush and John Kasich are at the opposite end of the spectrums. These data seem to suggest that voters view Trump as the most anti-establishment/populist candidate and Cruz as the most conservative candidate.
In contrast, voters seem to view Bush and Kasich as more moderate candidates closer to the so-called GOP establishment. Paul stands out, probably because he is viewed as outside the Washington establishment but his libertarian streak makes him appear more moderate than Cruz. Notably, Rubio straddles both the anti-establishment and establishment wings.