Akcora et al, SOMA 2010

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Cuneyt Gurcan Akcora, Murat Ali Bayir, Murat Demirbas, Hakan Ferhatosmanoglu, "Identifying BreakPoints in Public Opinion", SOMA 2010, SIGKDD Workshop on Social Media Analytics, Washington DC, USA.

Online version



The aim of this paper is to identify breakpoints in public opinion by capturing trends of public opinion from twitter data. The authors approach to this opinion detection problem by using vector space models.

After some observations, the authors claim that the emotion pattern and word pattern of tweets change as a result of a change in public opinion. With this aim in mind, authors developed an Emotion Corpus (Upinion) to detect emotions in tweets.

Two methods are used to detect opinions

  • Vector Space Model : A binary vector has been created for each tweet. Each class of the Emotion Corpus is represented as a dimension in the vector and the value of each dimension is determined by the existence of any emotion word from the related class in the tweet. Centroid of vectors are calculated to represent an interval. Cosine similarity is applied to centroid vectors to find the opinion similarity between two intervals.
  • Set Space Model : Each time interval is represented by a single document which is the union of tweets posted in that particular time interval. Jaccard similarity is used to find the similarity between two intervals.

The authors combine these two methods to detect a change and report a breakpoint.

In addition to detecting these changes, the authors also propose a tf-idf based scoring method to represent the breakpoints. They find the keywords by looking at the tfidf of the words while making sure that a word from the current time do not increase the prominence of the same word from an older time period.

The authors report the analysis of Tiger Wood's car accident topic in 2009. They found several possible breaks within the tweets and some of them are related to the events from reported news. They were also able to produce prominent words that describes the breakpoint.

Related to the paper, the authors produce a news tracking applicationon Twitter where a user can click on a period to see the events of the period with related prominent words.

A related work Ku et al, AAAI 2006 also focused on identifiying temporal changes in opinion by using language characteristics of Chinese.