Janette Lehmann
Pompeu Fabra University
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Publication
Featured researches published by Janette Lehmann.
international conference on user modeling adaptation and personalization | 2012
Janette Lehmann; Mounia Lalmas; Elad Yom-Tov; Georges Dupret
Our research goal is to provide a better understanding of how users engage with online services, and how to measure this engagement. We should not speak of one main approach to measure user engagement --- e.g. through one fixed set of metrics --- because engagement depends on the online services at hand. Instead, we should be talking of models of user engagement. As a first step, we analysed a number of online services, and show that it is possible to derive effectively simple models of user engagement, for example, accounting for user types and temporal aspects. This paper provides initial insights into engagement patterns, allowing for a better understanding of the important characteristics of how users repeatedly interact with a service or group of services.
international world wide web conferences | 2013
Janette Lehmann; Carlos Castillo; Mounia Lalmas; Ethan Zuckerman
Users interact with online news in many ways, one of them being sharing content through online social networking sites such as Twitter. There is a small but important group of users that devote a substantial amount of effort and care to this activity. These users monitor a large variety of sources on a topic or around a story, carefully select interesting material on this topic, and disseminate it to an interested audience ranging from thousands to millions. These users are news curators, and are the main subject of study of this paper. We adopt the perspective of a journalist or news editor who wants to discover news curators among the audience engaged with a news site. We look at the users who shared a news story on Twitter and attempt to identify news curators who may provide more information related to that story. In this paper we describe how to find this specific class of curators, which we refer to as news story curators. Hence, we proceed to compute a set of features for each user, and demonstrate that they can be used to automatically find relevant curators among the audience of two large news organizations.
conference on information and knowledge management | 2013
Janette Lehmann; Mounia Lalmas; Georges Dupret; Ricardo A. Baeza-Yates
Users often access and re-access more than one site during an online session, effectively engaging in multitasking. In this paper, we study the effect of online multitasking on two widely used engagement metrics designed to capture users browsing behavior with a site. Our study is based on browsing data of 2.5M users across 760 sites encompassing diverse types of services such as social media, news and mail. To account for multitasking we need to redefine how user sessions are represented and we need to adapt the metrics under study. We introduce a new representation of user sessions: tree-streams -- as opposed to the commonly used click-streams -- present a more accurate picture of the browsing behavior of a user that includes how users switch between sites (e.g., hyperlinking, teleporting, backpaging). We then discuss a number of insights on multitasking patterns, and show how these help to better understand how users engage with sites. Finally, we define metrics that characterize multitasking during online sessions and show how they provide additional insights to standard engagement metrics.
knowledge discovery and data mining | 2015
Mounia Lalmas; Janette Lehmann; Guy Shaked; Fabrizio Silvestri; Gabriele Tolomei
Click-through rate (CTR) is the most common metric used to assess the performance of an online advert; another performance of an online advert is the user post-click experience. In this paper, we describe the method we have implemented in Yahoo Gemini to measure the post-click experience on Yahoo mobile news streams via an automatic analysis of advert landing pages. We measure the post-click experience by means of two well-known metrics, dwell time and bounce rate. We show that these metrics can be used as proxy of an advert post-click experience, and that a negative post-click experience has a negative effect on user engagement and future ad clicks. We then put forward an approach that analyses advert landing pages, and show how these can affect dwell time and bounce rate. Finally, we develop a prediction model for advert quality based on dwell time, which was deployed on Yahoo mobile news stream app running on iOS. The results show that, using dwell time as a proxy of post-click experience, we can prioritise higher quality ads. We demonstrate the impact of this on users via A/B testing.
acm conference on hypertext | 2014
Janette Lehmann; Claudia Müller-Birn; David Laniado; Mounia Lalmas; Andreas Kaltenbrunner
Wikipedia is a collaboratively-edited online encyclopaedia that relies on thousands of editors to both contribute articles and maintain their quality. Over the last years, research has extensively investigated this group of users while another group of Wikipedia users, the readers, their preferences and their behavior have not been much studied. This paper makes this group and its %their activities visible and valuable to Wikipedias editor community. We carried out a study on two datasets covering a 13-months period to obtain insights on users preferences and reading behavior in Wikipedia. We show that the most read articles do not necessarily correspond to those frequently edited, suggesting some degree of non-alignment between user reading preferences and author editing preferences. We also identified that popular and often edited articles are read according to four main patterns, and that how an article is read may change over time. We illustrate how this information can provide valuable insights to Wikipedias editor community.
international conference on big data | 2013
Elad Yom-Tov; Mounia Lalmas; Ricardo A. Baeza-Yates; Georges Dupret; Janette Lehmann; Pinar Donmez
Many large online providers offer a variety of content sites (e.g. news, sport, e-commerce). These providers endeavor to keep users accessing and interacting with their sites, that is to engage users by spending time using their sites and to return regularly to them. They do so by serving users the most relevant content in an attractive and enticing manner. Due to their highly varied content, each site is usually studied and optimized separately. However, these online providers aim not only to engage users with individual sites, but across all sites in their network. In these cases, site engagement should be examined not only within individual sites, but also across the entire content provider network. This paper investigates intersite engagement, that is, site engagement within a network of sites, by defining a global measure of engagement that captures the effect sites have on the engagement on other sites. As an application, we look at the effect of web page layout and structure, which we refer to as web page stylistics, on intersite engagement on Yahoo! properties. Through the analysis of 50 popular Yahoo! sites and a sample of 265,000 users and 19.4M online sessions, we demonstrate that the stylistic components of a web page on a site can be used to predict inter-site engagement across the Yahoo! network of sites. Intersite engagement is a new big data problem as overall it implies analyzing dozen of sites visited by hundreds of millions of people generating billions of sessions.
conference on information and knowledge management | 2013
Janette Lehmann; Mounia Lalmas; Ricardo A. Baeza-Yates; Elad Yom-Tov
Online providers frequently offer a variety of services, ranging from news to mail. These providers endeavour to keep users accessing and interacting with the sites offering these services, that is to engage users by spending time on these sites and returning regularly to them. The standard approach to evaluate engagement with a site is by measuring engagement metrics of each site separately. However, when assessing engagement within a network of sites, it is crucial to take into account the traffic between sites. This paper proposes a methodology for studying networked used engagement. We represent sites (nodes) and user traffic (edges) between them as a network, and apply complex network metrics to study networked user engagement. We demonstrate the value of these metrics when applied to 728 services offered by Yahoo!~with a sample of 2M users and a total of 25M online sessions.
web intelligence | 2009
Claudia Müller-Birn; Janette Lehmann; Sabina Jeschke
Researchers of computer science and social science are increasingly interested in the Social Web and its applications. To improve existing infrastructures, to evaluate the success of available services, and to build new virtual communities and their applications, an understanding of dynamics and evolution of inherent social and informational structures is essential. One key question is how communities which exist in these applications are structured in terms of author contributions. Are there similar contribution patterns in different applications? For example, does the so called onion model revealed from open source software communities apply to Social Web applications as well? In this study, author contributions in the open content project Wikipedia are investigated. Previous studies to evaluate author contributions mainly concentrate on editing activities. Extending this approach, the added significant content and investigation of which author groups contribute the majority of content in terms of activity and significance are considered. Furthermore, the social information space is described by a dynamic collaboration network and the topic coverage of authors is analyzed. In contrast to existing approaches, the position of an author in a social network is incorporated. Finally, a new composite calculation to evaluate author contributions in Wikis is proposed. The action, the content contribution, and the connectedness of an author are integrated into one equation in order to evaluate author activity.
international world wide web conferences | 2012
Elad Yom-Tov; Mounia Lalmas; Georges Dupret; Ricardo A. Baeza-Yates; Pinar Donmez; Janette Lehmann
In the online world, user engagement refers to the phenomena associated with being captivated by a web application and wanting to use it longer and frequently. Nowadays, many providers operate multiple content sites, very different from each other. Due to their extremely varied content, these are usually studied and optimized separately. However, user engagement should be examined not only within individual sites, but also across sites, that is the entire content provider network. In previous work, we investigated networked user engagement, by defining a global measure of engagement that captures the effect that sites have on the engagement on other sites within the same browsing session. Here, we look at the effect of links on networked user engagement, as these are commonly used by online content providers to increase user engagement.
association for information science and technology | 2017
Janette Lehmann; Carlos Castillo; Mounia Lalmas; Ricardo A. Baeza-Yates
We study the news reading behavior of several hundred thousand users on 65 highly visited news sites. We focus on a specific phenomenon: users reading several articles related to a particular news development, which we call story‐focused reading. Our goal is to understand the effect of story‐focused reading on user engagement and how news sites can support this phenomenon. We found that most users focus on stories that interest them and that even casual news readers engage in story‐focused reading. During story‐focused reading, users spend more time reading and a larger number of news sites are involved. In addition, readers employ different strategies to find articles related to a story. We also analyze how news sites promote story‐focused reading by looking at how they link their articles to related content published by them, or by other sources. The results show that providing links to related content leads to a higher engagement of the users, and that this is the case even for links to external sites. We also show that the performance of links can be affected by their type, their position, and how many of them are present within an article.