Cited by 982Social Media and PoliticsElectoral Systems and Political ParticipationComputational and Text Analysis Methods

The DOI matches its Crossref record; 89 of the 89 references it cites were found in a registry or an index; 18 of the 56 sources its claims cite were checked for support.

Birds of the Same Feather Tweet Together: Bayesian Ideal Point Estimation Using Twitter Data

Open access
Barberá, Pablo·2015·Political Analysis

Abstract

Politicians and citizens increasingly engage in political conversations on social media outlets such as Twitter. In this article, I show that the structure of the social networks in which they are embedded can be a source of information about their ideological positions. Under the assumption that social networks are homophilic, I develop a Bayesian Spatial Following model that considers ideology as a latent variable, whose value can be inferred by examining which politics actors each user is following. This method allows us to estimate ideology for more actors than any existing alternative, at any point in time and across many polities. I apply this method to estimate ideal points for a large sample of both elite and mass public Twitter users in the United States and five European countries. The estimated positions of legislators and political parties replicate conventional measures of ideology. The method is also able to successfully classify individuals who state their political preferences publicly and a sample of users matched with their party registration records. To illustrate the potential contribution of these estimates, I examine the extent to which online behavior during the 2012 US presidential election campaign is clustered along ideological lines.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

The paper develops a Bayesian Spatial Following model that infers Twitter users’ and political actors’ latent ideology from whom they follow, under a homophily assumption. Applied to the US and five European countries, the estimates replicate conventional elite and mass ideology measures and reveal high polarization in 2012 US election retweet networks.

Key findings

  • US congressional Twitter ideal points correlate strongly with DW-NOMINATE: ρ = 0.941 in the House and ρ = 0.954 in the Senate; within-party correlations are ρ = 0.546 for Republicans and ρ = 0.610 for Democrats. European party placements are broadly congruent with Chapel Hill Expert Survey estimates, though the UK shows lower accuracy and some extreme parties appear more centrist.
  • Mass validation: self-identified conservatives are to the right of independents, who are to the right of liberals; state median Twitter ideal points correlate ρ = 0.876 with Lax and Phillips’s liberal-opinion estimates, higher than with the 2012 Obama vote (ρ = 0.785). Among matched campaign contributors, 90% of 1,058 right-of-median users donated to Republicans and 98% of 1,649 left-of-median users donated to Democrats; correlation with contribution-record ideal points is ρ = 0.80.
  • In the 2012 US election application, 65 million tweets mentioning Obama or Romney were sent by 8.8 million users; the analysis focuses on 15 million tweets from the 301,537-user sample. Moderates with ideal points between −0.5 and 0.5 are almost 40% of the sample but sent only 21% of tweets; conservative users (0.5 to 1.5) averaged 118 tweets versus 82 for users between −1.5 and −0.5.
  • Retweet interactions are highly polarized: 85% occur among users with similar ideological positions. For Obama retweets, 20% are in the bottom-left quadrant and 69% in the top-right; for Romney retweets, 49% are bottom-left and 31% top-right. Liberal users’ retweets include 18% from moderate/conservative users, while conservative users’ retweets include only 7% from liberal/moderate users.

Methods

  • The Bayesian Spatial Following model treats ideology as latent and models the probability that user i follows political actor j as logit⁻¹(α_j + β_i − ||θ_i − φ_j||²), where θ_i is the user’s ideal point, φ_j is the actor’s ideal point, α_j is actor popularity, and β_i is user political interest. Estimation uses hierarchical priors, a No-U-Turn/Hamiltonian Monte Carlo first stage and a random-walk Metropolis-Hastings second stage, implemented in Stan and R.
  • Data cover the US, UK, Spain, Germany, Italy, and the Netherlands. Target political actors with more than 5,000 followers in the US or 2,000 elsewhere number m = 318 US, 244 UK, 298 Spain, 214 Italy, 273 Germany, and 118 Netherlands. After filtering inactive, spam, out-of-country, and low-following accounts, final samples are n = 301,537 US, 135,015 UK, 123,846 Spain, 150,143 Italy, 49,142 Germany, and 96,624 Netherlands; the US sample is further restricted to accounts tweeting at least three times about Obama or Romney in the three months before the 2012 election.
  • Validation compares Twitter estimates with DW-NOMINATE, Chapel Hill Expert Survey placements, self-identified ideology, Lax and Phillips’s state opinion estimates, campaign contribution records, and Ohio voter registration records. The polarization application collects all public tweets mentioning Obama or Romney from August 15 to Election Day, totaling over 65 million tweets by 8.8 million users, and analyzes the 15 million tweets sent by the 301,537-user sample.

Limitations

  • Paper-stated: Twitter users are not a representative sample of the voting-age population; the sample is self-selected, more educated and politically interested, and restricted to users following at least three political accounts, so inferences do not represent all Twitter users. The paper argues this is not critical for estimating politicians’ ideal points.
  • Paper-stated: results across countries are not directly comparable because estimation is performed independently and the resulting dimension lacks a homogeneous cross-country scale. The method as formulated estimates ideology only for individuals who follow at least one political account, and the latent dimension may collapse different dimensions, especially in two-dimensional European party spaces; the UK shows lower accuracy and some extreme parties appear more centrist.
  • Paper-stated: the retweet polarization conclusion may be partly driven by the assumption that users are more likely to retweet someone they follow, though the text notes retweets between non-followers are frequent. Evident from the text: country location is inferred from profile fields, with country identified in 90% of cases and US state in 71%; the US sample is further restricted to accounts tweeting about Obama or Romney.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1093/pan/mpu011

Cites

89 of 89 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

18 of 56 cited sources checked · 9 supported · 2 flagged · accuracy not yet measured

Show all 79 claims

  • Probably not a substantial claim. 39
  • It may state two separate claims as one. 40
  • The quote only partly states this claim. 1
68 of 68
  • The authors state this as an assumption.

    Twitter users prefer to follow politicians whose positions on the latent ideological dimension are similar to theirs.

    “The key assumption of this model is that Twitter users prefer to follow politicians whose positions on the latent ideological dimension are similar to theirs.”
  • The paper relies on this without support.

    Most studies estimate ideal points for legislators only.

    “However, most studies estimate ideal points for legislators only.”
  • The paper relies on this without support.

    Citizens who discuss politics on Twitter are more likely to be educated and politically interested, and that makes them a particularly useful source of information about elites' ideology.

    “Citizens who discuss politics on Twitter are more likely to be educated and politically interested, and that makes them a particularly useful source of information about elites' ideology.”
  • The authors state this as an assumption.

    Following decisions are costly signals that provide information about Twitter users' perceptions of both their ideological location and that of political accounts.

    “I consider following decisions to be costly signals about users' perceptions of both their ideological location and that of political accounts.”
  • The paper relies on this without support.

    Virtually every legislator, political party, and candidate in developed democracies has an active Twitter account.

    “Virtually every legislator, political party, and candidate in developed democracies has an active Twitter account.”
  • The paper relies on this without support.

    Twitter users are embedded in a common social network.

    “Most importantly, they are embedded in a common social network.”
  • The authors state this as an assumption.

    The amount of time a user spends on Twitter is constant.

    “assuming the amount of time a user spends on Twitter is constant”
  • The authors state this as an assumption.

    Individual decisions to follow are independent across users n and m, conditional on the estimated parameters (local independence).

    “Assuming local independence (individual decisions to follow are independent across users n and m, conditional on the estimated parameters), the likelihood function to maximize this model is as follows:”
  • The authors state this as an assumption.

    The decision to follow a political actor is a function of the squared Euclidean distance in the latent ideological dimension between the user and the actor.

    “For the reasons explained above, I expect this decision to be a function of the squared Euclidean distance in the latent ideological dimension 5 between user i and j: À jj i À j jj 2”
  • The paper relies on this without support.

    Differences in the number of political accounts each user follows are related to the overall number of Twitter users they follow or their overall level of interest in politics.

    “Similarly, this parameter accounts for the differences in the number of political accounts each user i decides to follow, which could be related to the overall number of Twitter users they follow, or their overall level of interest in politics.”
  • The paper relies on this without support.

    Homophilic networks can be based not only on political traits, but also on other personal characteristics.

    “However, "homophilic" networks can be based not only on political traits, but also on other personal characteristics.”
  • The paper relies on this without support.

    High-quality ideology measures are available for a subset of all Twitter users in the US, UK, Spain, Germany, Italy, and the Netherlands.

    “However, in order to test the validity of the estimated parameters, I will focus on six countries where high-quality ideology measures are available for a subset of all Twitter users: the US, the UK, Spain, Germany, Italy, and the Netherlands.”
  • The paper relies on this without support.

    Users who follow three or more political accounts are more likely to be knowledgeable and interested in politics than the average citizen.

    “Precisely because they are more likely to be knowledgeable and interested in politics than the average citizen”
    “these users can indeed be considered as "authoritative" when it comes to politics.”
  • The paper relies on this without support.

    Many Twitter users define themselves politically in their profiles.

    “Here, I exploit the fact that many Twitter users define themselves politically in their profiles.”
  • The authors state this as an assumption.

    Users are more likely to retweet someone they follow.

    “It may be argued that this conclusion is driven at least in part by the key assumption behind the method to estimate ideology, since users are more likely to retweet someone they follow.”
  • The paper relies on this without support.

    As citizens spend a greater proportion of their time online, most of their political behavior also takes place through social networking platforms.

    “As citizens spend a greater proportion of their time online, most of their political behavior also takes place through social networking platforms.”
  • The paper relies on this without support.

    Most existing work relies on crude measures of political preferences.

    “Being able to estimate covariates of interest represents an important step in the study of such behavior, since most existing work relies on crude measures of political preferences.”
17 of 17

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Citations

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Research works printed but not linked: 2

  1. It may be argued that this conclusion is driven at least in part by the key assumption behind the method to estimate ideology, since users are more likely to retweet someone they follow. However, note that retweets between users who do not follow each other are indeed frequent. For example, of the 460,000 users who retweeted at least one of Barack Obama's tweets between August 15, 2012, and November 6, 2012, 152,000 (33%) did not follow him as of November 5, 2012. In fact, 21.2 of his 21.5 million followers at the time did not retweet any of his tweets during this period.
  2. King A. , Orlando F. , and Sparks D. B. 2011. Ideological extremity and primary success: A social network approach. Chicago, Illinois: Paper presented at the 2011 MPSA Conference.

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Metadata

Authors
Barberá, P.
Affiliations
New York University (US)
Corresponding author
Barberá, Pablo
Venue
Political Analysis
Published
2015
Volume
23
Issue
1
Pages
76-91
ISSN
  • 1047-1987 (ISSN-L)
  • 1476-4989
OpenAlex
W2161834943
Cited by
982
References
86
Citations by year
2026: 46 · 2025: 89 · 2024: 80 · 2023: 100 · 2022: 121 · 2021: 87 · 2020: 133 · 2019: 81 · 2018: 74 · 2017: 82 · 2016: 48 · 2015: 26
FWCI
165.45
Type
journal article
Language
en
Open access
Locations
  • Political Analysis (publishedVersion)
  • SSRN Electronic Journal (acceptedVersion)
  • London School of Economics and Political Science Research Online (London School of Economics and Political Science) (acceptedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
Funders
National Science Foundation (1248077)
Topics
  • Social Sciences › Communication › Social Media and Politics
  • Social Sciences › Political Science and International Relations › Electoral Systems and Political Participation
  • Social Sciences › General Social Sciences › Computational and Text Analysis Methods
Keywords
Twitter, ideal points, political debate, legislators, political parties, party registration, 2012 presidential election, online political behavior, latent variable models

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