Political Ideology and Issue Importance

• Author: Douglas Rice,David J. Barney,Brian F. Schaffner
• Published date: 01 December 2021
• Date: 01 December 2021
• DOI: http://doi.org/10.1177/1065912920967744
• Subject Matter: Articles

2021, Vol. 74(4) 1081 –1096

https://doi.org/10.1177/1065912920967744

Political Research Quarterly

© 2020 University of Utah

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DOI: 10.1177/1065912920967744

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Article

Introduction

Researchers have long understood that the salience of

issue attitudes varies considerably both across and within

individuals (Howe and Krosnick 2017). While these dif-

ferences have been leveraged to explain a number of dis-

crete outcomes, ranging from attitude accessibility

(Krosnick 1988) to candidate evaluation (Peterson 2004),

we know far less about how variations in attitude salience

affect composite measurements of public opinion such as

latent measures of political ideology. In particular,

because differences in issue salience constitute a form of

differential survey item functioning, it may be important

to account for issue salience in order to produce accurate

estimates of political ideology.

The resurgent debate regarding the impact of ideology

on Americans’ political behavior further motivates our

consideration of issue salience in latent measurement

(Fowler 2020). Many in the field view ideology as having

little, if any, effect on citizens’ political behavior; indeed,

recent studies find that ideology is only a weak predictor

of vote choice and other preferences (e.g. Kinder and

Kalmoe 2017). But such conclusions rest on measure-

ment approaches that do not incorporate individual-level

variations of issue salience into resulting estimates of ide-

ology. As such, past research might understate the impact

of political ideology on vote choice, representation, and

other political outcomes of interest.

In this paper, we employ several different models for

estimating latent ideology, each of which uses respon-

dents’ rating of issue importance. Each approach incor-

porates information about the preferences and salience

of each issue for a respondent, but incorporates salience

information in vastly different ways. One approach uses

salience as a weight in the estimation of latent ideology,

another uses salience weighting to recode responses in a

manner akin to rating scales, and a third employs salience

weights to select meaningful responses for latent trait

estimation. We assess the value-added from salience

weighting across these diverse approaches using two

survey data sets: (1) a subset of respondents to the 2016

Cooperative Congressional Election Study (CCES) and

(2) a sample of respondents recruited by the online pan-

elist recruitment firm Lucid. Throughout, we find that

the salience-weighted ideological scales do not produce

significantly better predictions of political outcomes of

interest, providing evidence that accounting for issue

967744PRQXXX10.1177/1065912920967744Political Research QuarterlyRice et al.

research-article2020

1University of Massachusetts Amherst, USA

2Tufts University, Medford, MA, USA

3Burning Glass Technologies, Boston, MA, USA

Corresponding Author:

Brian F. Schaffner, Tufts University, Packard Hall, Medford, MA 02155,

USA.

Email: brian.schaffner@tufts.edu

Political Ideology and

Issue Importance

Douglas Rice1, Brian F. Schaffner2, and David J. Barney3

Abstract

Past research has shown that issues vary significantly in their salience across citizens, explaining key outcomes in

political behavior. Yet it remains unclear how individual-level differences in issue salience affect the measurement of

latent constructs in public opinion, namely political ideology. In this paper, we test whether scaling approaches that

fail to incorporate individual-level differences in issue salience could understate the predictive power of ideology in

public opinion research. To systematically examine this assertion, we employ a series of latent variable models which

incorporate both issue importance and issue position. We compare the results of these different and diverse scaling

approaches to two survey data sets, investigating the implications of accounting for issue salience in constructing

latent measures of ideology. Ultimately, we find that accounting for issue importance adds little information to a more

basic approach that uses only issue positions, suggesting ideological signals for measurement models reside most

prominently in the issue positions of individuals rather than the importance of those issues to the individual.

Keywords

political ideology, issue importance, issue salience, item response theory

1082 Political Research Quarterly 74(4)

2 Political Research Quarterly 00(0)

salience does not improve commonly used scaling

approaches for measuring ideology.

Accounting for Issue Importance in

Political Ideology

Public opinion scholars have long recognized that while

citizens hold multiple attitudes at the same time, not all

attitudes hold equal weight across citizens. Some might

care most deeply about their Second Amendment rights

and care little about tax policy, while another might care

deeply about tax policy while remaining relatively

agnostic on the Second Amendment. Scholars often dis-

tinguish between objective or contextual salience—

where an issue is receiving a great deal of attention from

important actors in the political system—and subjective

or individual salience—where an issue is particularly

important to some people but less important to others

(Lecheler, de Vreese, and Slothuus 2009). While these

two dimensions are surely interrelated, we explore

whether it is individual-level issue importance that may

be an important missing piece from how individuals’

ideologies are currently estimated.

It is clear that individuals express far more concern for

certain issues than others, relying on their most salient

attitudes for decision-making (Howe and Krosnick 2017;

Krosnick, Berent, and Boninger 1994). This concept—

which we refer to as both attitude salience and issue

importance (Ansolabehere and Puy 2018; Bernstein

1995; Boninger, Krosnick, and Berent 1995)—explains

key features of political behavior, including political par-

ticipation (Holbrook et al. 2016), information processing

(Ciuk and Yost 2016), political learning (Nadeau, Niemi,

and Amato 1995), attitude accessibility (Krosnick 1988),

and attitude stability (Krosnick 1990).1 Of more debate is

whether attitude salience is a significant predictor of vote

choice. Peterson (2004) finds evidence that voters do rely

on such attitudes in candidate evaluation; however,

Leeper and Robison (2020) uncover little support for the

idea that people are more likely to engage in “issue vot-

ing” on issues that they rate as being more important to

them. Likewise, Lau, Andersen, and Redlawsk (2008)

find that accounting for issue importance makes little dif-

ference for whether an individual is found to have voted

correctly.

While the differential influence of issue attitudes has

informed our understanding of many discrete outcomes,

it remains less clear how variation in issue salience might

affect the estimation of composite measures of public

opinion, most notably the latent scaling of political ideol-

ogy. Researchers often summarize a citizen’s political

ideology by scaling a number of issue attitudes together

with a latent variable technique (see, e.g., Laver 2014),

producing an estimate that represents a citizen’s “ideal

point” of issue preferences along a single dimension

(Ansolabehere, Rodden, and Snyder 2008; Berinsky

2017; Erikson, MacKuen, and Stimson 2002; Jacoby

1995).2 In this paper, we explore variation in issue

salience as a particular form of differential item function-

ing (DIF), which is characterized by items that exhibit

different functioning along the dimension of latent ideol-

ogy for different subgroups of respondents. In our area of

interest, take for example an item that operates differently

for men and women of similar ideological perspectives.

Variation in issue salience across respondents constitutes

another potential form of DIF, and one that if addressed

could hypothetically improve latent estimates of political

ideology. Critically, it is also one here that we do not

detect or estimate, but rather is one that we know by vir-

tue of survey items explicitly asking respondents to report

how important the underlying topic of the question is to

them.

Therefore, methodologically speaking, the incorpora-

tion of issue salience potentially provides a simple but

important intervention for latent variable approaches. In

standard latent variable models, particular items may be

more strongly associated with (or discriminating of) the

underlying dimension, thus contributing more to esti-

mates of the latent trait among all respondents (Bollen

2002). Allowing some issues to contribute more informa-

tion to the estimation of the population’s ideology is one

way to account for objective or contextual salience.

Issues that are attracting more attention from politicians

and the news media may naturally provide more informa-

tion about the public’s ideology. However, because stan-

dard models specify the operation of items at the global

level, such approaches fail to address individual-level dif-

ferences in issue importance. If some members of the

public care quite deeply about the issue of gun control,

then their views on that issue are likely to be more

strongly driven by their underlying ideology. By contrast,

when an issue is not particularly important to a group of

people, their views on that issue may be less reflective of

their ideology.

Existing work on individual-level issue importance

provides some evidence for why we might expect this

dynamic. For example, Lecheler, de Vreese, and Slothuus

(2009) find that issue framing has no effect on attitudes

on issues that are very important to individuals, but that

the effects are much stronger on less important issues (see

also Arceneaux 2008). Given that an important aspect of

ideological thinking is issue constraint (Converse 1964),

it is significant that people are more resistant to changing

their views on issues that they identify as important to

them. Additionally, Hill and Huber (2019) find that peo-

ple express more confidence in the issue positions they

take on issues that are more important to them. In short,

these research studies suggest that when an issue is