2,759 research outputs found
Event detection in location-based social networks
With the advent of social networks and the rise of mobile technologies, users have become ubiquitous sensors capable of monitoring various real-world events in a crowd-sourced manner. Location-based social networks have proven to be faster than traditional media channels in reporting and geo-locating breaking news, i.e. Osama Bin Laden’s death was first confirmed on Twitter even before the announcement from the communication department at the White House. However, the deluge of user-generated data on these networks requires intelligent systems capable of identifying and characterizing such events in a comprehensive manner. The data mining community coined the term, event detection , to refer to the task of uncovering emerging patterns in data streams . Nonetheless, most data mining techniques do not reproduce the underlying data generation process, hampering to self-adapt in fast-changing scenarios. Because of this, we propose a probabilistic machine learning approach to event detection which explicitly models the data generation process and enables reasoning about the discovered events. With the aim to set forth the differences between both approaches, we present two techniques for the problem of event detection in Twitter : a data mining technique called Tweet-SCAN and a machine learning technique called Warble. We assess and compare both techniques in a dataset of tweets geo-located in the city of Barcelona during its annual festivities. Last but not least, we present the algorithmic changes and data processing frameworks to scale up the proposed techniques to big data workloads.This work is partially supported by Obra Social “la Caixa”, by the Spanish Ministry of Science and Innovation under contract (TIN2015-65316), by the Severo Ochoa Program (SEV2015-0493), by SGR programs of the Catalan Government (2014-SGR-1051, 2014-SGR-118), Collectiveware (TIN2015-66863-C2-1-R) and BSC/UPC NVIDIA GPU Center of Excellence.We would also like to thank the reviewers for their constructive feedback.Peer ReviewedPostprint (author's final draft
Characterizing Geo-located Tweets in Brazilian Megacities
This work presents a framework for collecting, processing and mining
geo-located tweets in order to extract meaningful and actionable knowledge in
the context of smart cities. We collected and characterized more than 9M tweets
from the two biggest cities in Brazil, Rio de Janeiro and S\~ao Paulo. We
performed topic modeling using the Latent Dirichlet Allocation model to produce
an unsupervised distribution of semantic topics over the stream of geo-located
tweets as well as a distribution of words over those topics. We manually
labeled and aggregated similar topics obtaining a total of 29 different topics
across both cities. Results showed similarities in the majority of topics for
both cities, reflecting similar interests and concerns among the population of
Rio de Janeiro and S\~ao Paulo. Nevertheless, some specific topics are more
predominant in one of the cities
Characterizing Geo-located Tweets in Brazilian Megacities
This work presents a framework for collecting, processing and mining
geo-located tweets in order to extract meaningful and actionable knowledge in
the context of smart cities. We collected and characterized more than 9M tweets
from the two biggest cities in Brazil, Rio de Janeiro and S\~ao Paulo. We
performed topic modeling using the Latent Dirichlet Allocation model to produce
an unsupervised distribution of semantic topics over the stream of geo-located
tweets as well as a distribution of words over those topics. We manually
labeled and aggregated similar topics obtaining a total of 29 different topics
across both cities. Results showed similarities in the majority of topics for
both cities, reflecting similar interests and concerns among the population of
Rio de Janeiro and S\~ao Paulo. Nevertheless, some specific topics are more
predominant in one of the cities
Social influence analysis in microblogging platforms - a topic-sensitive based approach
The use of Social Media, particularly microblogging platforms such as Twitter, has proven to be an effective channel for promoting ideas to online audiences. In a world where information can bias public opinion it is essential to analyse the propagation and influence of information in large-scale networks. Recent research studying social media data to rank users by topical relevance have largely focused on the “retweet", “following" and “mention" relations. In this paper we propose the use of semantic profiles for deriving influential users based on the retweet subgraph of the Twitter graph. We introduce a variation of the PageRank algorithm for analysing users’ topical and entity influence based on the topical/entity relevance of a retweet relation. Experimental results show that our approach outperforms related algorithms including HITS, InDegree and Topic-Sensitive PageRank. We also introduce VisInfluence, a visualisation platform for presenting top influential users based on a topical query need
Measuring relative opinion from location-based social media: A case study of the 2016 U.S. presidential election
Social media has become an emerging alternative to opinion polls for public
opinion collection, while it is still posing many challenges as a passive data
source, such as structurelessness, quantifiability, and representativeness.
Social media data with geotags provide new opportunities to unveil the
geographic locations of users expressing their opinions. This paper aims to
answer two questions: 1) whether quantifiable measurement of public opinion can
be obtained from social media and 2) whether it can produce better or
complementary measures compared to opinion polls. This research proposes a
novel approach to measure the relative opinion of Twitter users towards public
issues in order to accommodate more complex opinion structures and take
advantage of the geography pertaining to the public issues. To ensure that this
new measure is technically feasible, a modeling framework is developed
including building a training dataset by adopting a state-of-the-art approach
and devising a new deep learning method called Opinion-Oriented Word Embedding.
With a case study of the tweets selected for the 2016 U.S. presidential
election, we demonstrate the predictive superiority of our relative opinion
approach and we show how it can aid visual analytics and support opinion
predictions. Although the relative opinion measure is proved to be more robust
compared to polling, our study also suggests that the former can advantageously
complement the later in opinion prediction
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