Browsing by Author "Elejalde, Erick"

Now showing 1 - 6 of 6
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    On the nature of real and perceived bias in the mainstream media
    (2018) Elejalde, Erick; Ferres, Leo; Herder, Eelco
    News consumers expect news outlets to be objective and balanced in their reports of events and opinions. However, there is a growing body of evidence of bias in the media caused by underlying political and socio-economic viewpoints. Previous studies have tried to classify the partiality of the media, but there is little work on quantifying it, and less still on the nature of this partiality. The vast amount of content published in social media enables us to quantify the inclination of the press to pre-defined sides of the socio-political spectrum. To describe such tendencies, we use tweets to automatically compute a news outlet’s political and socio-economic orientation. Results show that the media have a measurable bias, and illustrate this by showing the favoritism of Chilean media for the ruling political parties in the country. This favoritism becomes clearer as we empirically observe a shift in the position of the mass media when there is a change in government. Even though relative differences in bias between news outlets can be observed, public awareness of the bias of the media landscape as a whole appears to be limited by the political space defined by the news that we receive as a population. We found that the nature of the bias is reflected in the vocabulary used and the entities mentioned by different news outlets. A survey conducted among news consumers confirms that media bias has an impact on the coverage of controversial topics and that this is perceivable by the general audience. Having a more accurate method to measure and characterize media bias will help readers position outlets in the socio-economic landscape, even when a (sometimes opposite) self-declared position is stated. This will empower readers to better reflect on the content provided by their news outlets of choice.
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    Parallel construction of wavelet trees on multicore architectures
    (01/06/2017) Fuentes-Sepúlveda, José; Elejalde, Erick; Ferres, Leo; Seco, Diego
    The wavelet tree has become a very useful data structure to efficiently represent and query large volumes of data in many different domains, from bioinformatics to geographic information systems. One problem with wavelet trees is their construction time. In this paper, we introduce two algorithms that reduce the time complexity of a wavelet tree's construction by taking advantage of nowadays ubiquitous multicore machines. Our first algorithm constructs all the levels of the wavelet in parallel with O(n) time and bits of working space, where n is the size of the input sequence and is the size of the alphabet. Our second algorithm constructs the wavelet tree in a domain decomposition fashion, using our first algorithm in each segment, reaching time and bits of extra space, where p is the number of available cores. Both algorithms are practical and report good speedup for large real datasets.
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    Power structure in Chilean news media
    (2018) Bahamonde, Jorge; Bollen, Johan; Elejalde, Erick; Ferres, Leo; Poblete, Bárbara
    Even democracies endowed with the most active free press struggle to maintain diversity of news coverage. Consolidation and market forces may cause only a few dominant players to control the news cycle. Editorial policies may be biased by corporate ownership relations, narrowing news coverage and focus. To an increasing degree this problem also applies to social media news distribution, since it is subject to the same socio-economic drivers. To study the effects of consolidation and ownership on news diversity, we model the diversity of Chilean coverage on the basis of ownership records and social media data. We create similarity networks of news outlets on the basis of their ownership and the topics they cover. We then examine the relationships between the topology of ownership networks and content similarity to characterize how ownership affects news coverage. A network analysis reveals that Chilean media is highly concentrated both in terms of ownership as well as in terms of topics covered. Our method can be used to determine which groups of outlets and ownership exert the greatest influence on news coverage.
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    Quantifying the ecological diversity and health of online news
    (2018) Elejalde, Erick; Ferres, Leo; Herder, Eelco; Bollen, Johan
    Even in developed countries with an active free press, news coverage can be dominated by only a few players. This can lead to a reduction of topical and community diversity. Ownership structures might further limit coverage by implicitly or explicitly biasing editorial policies. In this paper, we apply ecological diversity measures to quantify the health of the Chilean online news ecology using extensive ownership and social media data. Results indicate that high levels concentration characterizes the Chilean media landscape in terms of ownership and topical coverage. Our methods reveal which groups of outlets and ownership exert the greatest influence on news coverage and can be generalized to any nation's news system.
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    The Nature of Real and Perceived Bias in Chilean Media
    (2017) Elejalde, Erick; Ferres, Leo; Herder, Eelco
    News consumers expect news outlets to be objective and balanced in their reports of events. However, there is a body of evidence of bias in the media caused by underlying political and socio-economic viewpoints. Previous studies have tried to classify the partiality of the media, sometimes giving a quantitative evaluation, but there is little reported on its nature. The vast amount of content in the social media enables us to quantify the inclination of the press to either side of the political spectrum. To describe such tendencies, we use tweets to automatically compute a news outlet's political and socio-economic orientation. We show that the media have a measurable bias, and illustrate this by showing the favoritism of Chilean media for the ruling political parties in this country. We also found that the nature of the bias is reflected in the vocabulary used and the entities mentioned by different news outlets. A survey conducted among news consumers confirms that media bias has an impact on the coverage of controversial topics and that this is perceivable by the general audience. Having a more accurate method to measure and characterize media bias will clarify to the readers where outlets stand within the socio-economic landscape, even when a self-declared position is stated. This will empower readers to better reflect on the content provided by their news outlets of choice.
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    Understanding news outlets’ audience-targeting patterns
    (2019) Ferres, Leo; Elejalde, Erick; Schifanella, Rossano
    The power of the press to shape the informational landscape of a population is unparalleled, even now in the era of democratic access to all information outlets. However, it is known that news outlets (particularly more traditional ones) tend to discriminate who they want to reach, and who to leave aside. In this work, we attempt to shed some light on the audience targeting patterns of newspapers, using the Chilean media ecosystem. First, we use the gravity model to analyze geography as a factor in explaining audience reachability. This shows that some newspapers are indeed driven by geographical factors (mostly local news outlets) but some others are not (national-distribution outlets). For those which are not, we use a regression model to study the influence of socioeconomic and political characteristics in news outlets adoption. We conclude that indeed larger, national-distribution news outlets target populations based on these factors, rather than on geography or immediacy.

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