Below, we use Aldrich-McKelvey scaling (see here and here for background) to analyze voters’ ideological perceptions of the 2016 presidential candidates and other political figures. The 2016 pilot study of the American National Election Study asked respondents to place themselves and each of these figures on a seven-point ideological scale ranging from “extremely liberal” to “extremely conservative.” The Aldrich-McKelvey scaling procedure allows us to recover bias-corrected estimates of the respondents and candidates on the underlying ideological dimension.

The estimated scores (plotted below) show that three Democratic figures (the Democratic Party, President Obama, and Secretary Clinton) are ideologically clustered together. Clinton is a bit closer to the center than the other two, but not by much. On the other hand, there is considerable heterogeneity in ideological perceptions of the four Republican stimuli: Senator Rubio, Donald Trump, the Republican Party, Senator Cruz. It’s probably not surprising that Rubio is perceived to be the most moderate and Cruz is perceived to be the most conservative of the four.

What is noteworthy is that Trump is placed at nearly the same spot as Rubio. Trump, however, has the the greatest amount of uncertainty associated with his ideological score (as a technical note, we estimate 95% confidence intervals for the Aldrich-McKelvey scores using 1,000 bootstrap replications, as described in Chapter 3 of our book on estimating spatial models).

This is equivalent to saying that respondents differ the most in where they place Trump on the ideological scale. The width of Trump’s confidence interval is about twice that of Clinton’s, for instance. This uncertainty could be a factor in the 2016 race, as some political science research suggests that voters reward candidate ambiguity (see also here).

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We wondered if voter uncertainty about Trump’s ideological position was being driven by a divide among self-identified conservative respondents; that is, between those who embrace Trump and believe he’s a conservative, and those (e.g., #NeverTrumpers) who doubt Trump’s conservative credentials. To look into this possibility, we plotted the mean placements of Trump and Clinton by respondents’ ideological self-identifications. “1” indicates extremely liberal, “2” indicates liberal, and so on until “7” for extremely conservative. Respondents are sorted in this way on on the vertical axis of the graph below.

For each ideological category of respondents, mean placements of Clinton and Trump are shown along the same seven-point liberal-conservative scale on the horizontal axis. For example, the most conservative respondents (self-identified “7”‘s or extremely conservative) place Clinton furthest to the left. The gray bars represent variation in the corresponding group’s ideological placements of Clinton and Trump.

Interesting, across the ideological categories, respondents are pretty evenly uncertain about Trump’s position on the liberal-conservative scale. On the whole, self-identified conservatives do view Trump as somewhat more moderate than do self-identified liberals (evidence of what is known as interpersonal incomparability or differential item-functioning). But, it is self-identified moderates who place Trump closest to the center (and have the least variation in their Trump placements).

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