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論文題目：USING SOCIAL MEDIA TO MEASURE POLITICAL POLARIZATION; A TWITTER ANALYSIS OF DONALD TRUMP'S FIRST 40 DAYS IN OFFICE
著者：ホセイン・ ヌラニ （Nourani Hossein）
論文審査委員：ジョナサン・ルイス、中野聡、赤嶺淳、福富満久
1. Outline of the Thesis
This thesis investigates the phenomenon of political polarization in the contemporary United States, as revealed in the communications of Twitter users during the first forty days of the Trump Administration in early 2017. In particular, it aims to establish the relationship between American social media users’ ideological positions and their views on individual political issues. In other words, it examines the extent to which social media users disagree with a politician on certain issues despite holding a generally positive attitude towards them. In this case, the politician is Donald Trump, and the issues are five topics that were widely written about in tweets mentioning the word “Trump” during the first 40 days of the new presidency: foreign affairs in general, US-Russian relations, immigration, civil affairs and the environment.
The dataset of tweets containing the word “Trump” was cleaned to remove duplicates, retweets and non-English tweets. Because the author was interested in the views of Twitter users actively engaged in political debate, he further reduced the dataset to tweets containing the name of at least one other user and who were members of the four largest clusters of users engaging in political debate. The final dataset contained 159, 791 tweets sent by 58,880 users between 20 January and 4 March 2017. The author then manually coded the 1,000 hashtags used most frequently in those tweets both by attitude to Trump (pro-, anti- and neutral) and the five topics mentioned above. Using these codes, he then identified 1,895 and 3,739 pro- and anti-Trump users respectively, based on whether they used attitudinal hashtags in at least 60% of their tweets. He also classified these users’ positions on the five issues based on their hashtags. He found that both pro- and anti-Trump users showed very little tendency to align differently with Trump on specific issues compared to their general attitude towards him. On the other hand, anti-Trump users were somewhat more issue-specific and more diverse than pro-Trump users when expressing their attitudes. Overall, however, hashtags expressing general support for opposition to Trump far outnumbered hashtags on specific issues. The author tentatively concludes from this that most Twitter users choose their political position according to ideology rather than their personal opinions on specific issues.
2. Evaluation of the Thesis
This thesis takes on the challenge of doing empirical research in a fast-moving area where we still lack a systematic understanding of the use of social media by both politicians and the general population, and where research methods are also changing rapidly.
Its main contribution is methodological. Most previous studies of political polarization using Twitter data have first used hashtags to identify political tweets, then extracted retweet, mention and follower connections from the resulting dataset and finally analyzed the resulting connections to draw conclusions about whether users are interacting with users holding different views from their own. In contrast, Mr. Hossein uses network analysis at the preliminary stage in order to identify those users engaging in Trump-related information exchange, and then uses manual content analysis of hashtags in order to identify users’ positions. Both approaches have their strengths and weaknesses, but Mr. Hossein’s original combination of quantitative and qualitative analysis allows him to take more account of the particular issues on which users are expressing their views.
The thesis also lays the groundwork for a more extended study of the relationship between ideology, party support and issue-specific attitudes. His finding that users tweeting about Trump, and especially those supporting him, made relatively little mention of specific issues, opens up promising avenues of research such as whether this is a phenomenon specific to Trump, or to Republic candidates. Another question would be whether users tweet about specific issues separately from their expressions of support of or opposition to particular candidates.
The thesis also provokes the reader to think about how country (i.e. U.S.)-specific the current research on political polarization and social media is, and indeed on whether the research method developed here could be applied to political systems other than liberal democracies.
最終試験の結果の要旨
2018年6月13日
On 9 April 2018 we examined Mr. Hossein Nourani regarding his PhD thesis “Using Social Media to Measure Political Polarization: A Twitter Analysis of Donald Trump’s First 40 Days in Office.” Mr. Nourani satisfactorily answered all our questions regarding his thesis.
We therefore conclude that Mr. Nourani has achieved the requisite level of academic achievement and ability to be awarded the degree of PhD in Social Sciences from this University in accordance with Article 5 Section 1 of the Hitotsubashi University Degree Regulations.
2018年4月9日、学位請求論文提出者ホセイン・ヌラニ氏についての最終試験を行った。本試験において、審査委員が提出論文『政治的分極化を測定するツールとしてのソーシャルメディア―ドナルド・トランプ大統領就任後４０日間のツイッター分析―』について、逐一疑問点について説明を求めたのに対し、ホセイン氏はいずれも十分な説明を与えた。
以上により、審査委員一同はホセイン・ヌラニ氏が本論文の筆者が一橋大学学位規則第5条第１項の規定により一橋大学博士（社会学）の学位を授与されるのに必要な研究業績および学力を有するものと認定した。