Online Popularity and Topical Interests through the Lens of Instagram

Online socio-technical systems can be studied as proxy of the real world to investigate human behavior and social interactions at scale. Here we focus on Instagram, a media-sharing online platform whose popularity has been rising up to gathering hundred millions users. Instagram exhibits a mixture of features including social structure, social tagging and media sharing. The network of social interactions among users models various dynamics including follower/followee relations and users' communication by means of posts/comments. Users can upload and tag media such as photos and pictures, and they can "like" and comment each piece of information on the platform. In this work we investigate three major aspects on our Instagram dataset: (i) the structural characteristics of its network of heterogeneous interactions, to unveil the emergence of self organization and topically-induced community structure; (ii) the dynamics of content production and consumption, to understand how global trends and popular users emerge; (iii) the behavior of users labeling media with tags, to determine how they devote their attention and to explore the variety of their topical interests. Our analysis provides clues to understand human behavior dynamics on socio-technical systems, specifically users and content popularity, the mechanisms of users' interactions in online environments and how collective trends emerge from individuals' topical interests.Comment: 11 pages, 11 figures, Proceedings of ACM Hypertext 201

Crowd-sourced Photographic Content for Urban Recreational Route Planning

Routing services are able to provide travel directions for users of all modes of transport. Most of them are focusing on functional journeys (i.e. journeys linking given origin and destination with minimum cost) while paying less attention to recreational trips, in particular leisure walks in an urban context. These walks are additionally predefined by time or distance and as their purpose is the process of walking itself, the attractiveness of areas that are passed by can be an important factor in route selection. This factor is hard to be formalised and requires a reliable source of information, covering the entire street network. Previous research shows that crowd-sourced data available from photo-sharing services has a potential for being a measure of space attractiveness, thus becoming a base for a routing system that suggests leisure walks, and ongoing PhD research aims to build such system. This paper demonstrates findings on four investigated data sources (Flickr, Panoramio, Picasa and Geograph) in Central London and discusses the requirements to the algorithm that is going to be implemented in the second half of this PhD research. Visual analytics was chosen as a method for understanding and comparing obtained datasets that contain hundreds of thousands records. Interactive software was developed to find a number of problems, as well as to estimate the suitability of the sources in general. It was concluded that Picasa and Geograph have problems making them less suitable for further research while Panoramio and Flickr require filtering to remove photographs that do not contribute to understanding of local attractiveness. Based on this analysis a number of filtering methods were proposed in order to improve the quality of datasets and thus provide a more reliable measure to support urban recreational routing

Preserving Social Media: the Problem of Access

As the applications and services made possible through Web 2.0 continue to proliferate and influence the way individuals exchange information, the landscape of social science research, as well as research in the humanities and the arts, has the potential to change dramatically and to be enriched by a wealth of new, user-generated data. In response to this phenomenon, the UK Data Service have commissioned the Digital Preservation Coalition to undertake a 12-month study into the preservation of social media as part of the ‘Big Data Network’ programme funded by the Economic and Social Research Council (ESRC). The larger study focuses on the potential uses and accompanying challenges of data generated by social networking applications. This paper, ‘Preserving Social Media: the Problem of Access’, comprises an excerpt of that longer study, allowing the authors a space to explore in closer detail the issue of making social media archives accessible to researchers and students now and in the future. To do this, the paper addresses use cases that demonstrate the potential value of social media to academic social science. Furthermore, it examines how researchers and collecting institutions acquire and preserve social media data within a context of curatorial and legislative restrictions that may prove an even greater obstacle to access than any technical restrictions. Based on analysis of these obstacles, it will examine existing methods of curating and preserving social media archives, and second, make some recommendations for how collecting institutions might approach the long-term preservation of social media in a way that protects the individuals represented in the data and complies with the conditions of third party platforms. With the understanding that web-based communication technologies will continue to evolve, this paper will focus on the overarching properties of social media, analysing and comparing current methods of curation and preservation that provide sustainable solutions

Sources of inflation and output fluctuations in Poland and Hungary: Implications for full membership in the European Union

This paper examines the sources of fluctuations in inflation and output in two leading transitioneconomy candidates for admission to the European Union (EU), Poland and Hungary. Using a rational expectations, dynamic open economy aggregate supply- aggregate demand model, we consider real oil price, supply, balance of payments, demand, and monetary disturbances incorporating important features of transition economies such as balance of payments disturbances and finite capital mobility. Evidence indicates that supply shocks explain a sizable portion of price level movements in Hungary while demand shocks are dominant in price level movements in Poland. Monetary shocks are an important source of output fluctuations in the short run in Hungary suggesting nominal inertia. In Poland, real demand shocks affect output in the short run (up to one year), while monetary shocks are negligible. Estimates of “core inflation” based on historical realizations of the shocks suggest that a major component of inflation has been demand driven, “core” inflation. Finally, policy implications of these findings regarding EU membership are evaluated. --Business Cycles,Inflation,Transition Economies,Time Series Models

Robust determinants of bilateral trade

What are the policies and country-level conditions which best explain bilateral trade flows between countries? As databases expand, an increasing number of possible explanatory variables are proposed that influence bilateral trade without a clear indication of which variables are robustly important across contexts, time periods, and which are not sensitive to inclusion of other control variables. To shed light on this problem, we apply three model selection methods – Lasso reguarlized regression, Bayesian Model Averaging, and Extreme Bound Analysis -- to candidate variables in a gravity models of trade. Using a panel of 198 countries covering the years 1970 to 2000, we find model selection methods suggest many fewer variables are robust that those suggested by the null hypothesis rejection methodology from ordinary least squares

Fear of floating and fear of pegging: An empirical anaysis of de facto exchange rate regimes in developing countries

This paper uses a panel probit model with simultaneous equations to explain the joint determination of de facto and de jure exchange rate regimes in developing countries since 1980. We also derive an ordered-choice panel probit model to explain the causes of discrepancies between the two regime choices. Both models are estimated using simulation-based maximum likelihood methodsl. The results of the simultaneous equations model suggest that the two regime choices are dependent of each other and exhibit considerable state dependence. The ordered probit model provides evidence that regime discrepancies reflect an error-correction mechanism, and the discrepancies are persistent over time. --de facto exchange rate regimes,developing countries,simultaneous equations model,simulated maximum likelihood