Manolis Tzagarakis

Manolis Tzagarakis
University of Patras | UP · Department of Economics

About

126
Publications
37,577
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478
Citations
Citations since 2017
10 Research Items
166 Citations
20172018201920202021202220230102030
20172018201920202021202220230102030
20172018201920202021202220230102030
20172018201920202021202220230102030
Additional affiliations
April 2013 - present
University of Patras
Position
  • Professor (Assistant)
April 2013 - present
University of Patras
Position
  • Professor (Assistant)

Publications

Publications (126)
Article
We study the predictive value of transaction activity in the bitcoin network for the realized volatility of bitcoin returns constructed by high-frequency data. As an alternative modeling approach to the popular linear heterogeneous autoregressive model, we provide out-of-sample forecasts for realized volatility of bitcoin returns employing machine...
Article
Full-text available
We investigate the impact of non-cognitive skills on the quality of task-specific outcomes by conducting a quasi-experiment on a well-known online crowdsourcing platform. We show that worker’s performance varies with personality traits, gender, human capital, crowdsourcing experience and work effort. Regarding the effects of non-cognitive skills, w...
Chapter
Crowdsourcing is a new form of online labor, where the process of solving a problem is approached by soliciting contributions from a large group of people. In this paper, the authors attempt to investigate how different incentives affect the quality of work in such contexts, by completing the same task in three different environments: in a laborato...
Chapter
Crowdsourcing is a new form of online labor, where the process of solving a problem is approached by soliciting contributions from a large group of people. In this paper, the authors attempt to investigate how different incentives affect the quality of work in such contexts, by completing the same task in three different environments: in a laborato...
Article
Full-text available
Nowadays, the economic activities have become increasingly digital since hundreds of millions of Internet users are using crowdsourcing platforms either to work at an online job as workers, or as a model of problem-solving and production as requesters. This growing workforce makes it necessary from the perspective of the online platforms, to fully...
Poster
Full-text available
The idea to associate information with so-called links was developed by hypertext pioneers in the 1960s. In the 1990s the Dexter Hypertext Reference Model was developed with the goal to provide a general model for node-link hypertext systems. In the 1990s and 2000s there were important steps made for hypertext infrastructures, which led to componen...
Conference Paper
Full-text available
The idea to associate information with so-called links was developed by hypertext pioneers in the 1960s. In the 1990s the Dexter Hypertext Reference Model was developed with the goal to provide a general model for node-link hypertext systems. In the 1990s and 2000s there were important steps made for hypertext infrastructures, which led to componen...
Conference Paper
Full-text available
Today hundreds of millions of Internet users are using crowdsourcing platforms either to work to an online job as workers, or as a model of problem solving and production as requesters. This growing workforce makes it necessary from the perspective of the online platforms, to fully understand the factors which contribute on this emerging and innova...
Conference Paper
Full-text available
Specialized systems aiming at offering hypertext functionality in users' computing have been discussed since the early days of hypertext. However, with the claim to also support other structure domains than node-link structures, hypertext systems had to overcome some challenges. Researchers came up with component-based approaches and low level stru...
Article
Full-text available
Today hundreds of millions of Internet users are using crowdsourcing platforms either to work to an online job as workers, or as a model of problem solving and production as requesters. This growing workforce makes it necessary from the perspective of the online platforms, to fully understand the factors which contribute on this emerging and innova...
Chapter
Collaborative decision making in today’s knowledge intensive and multi-disciplinary environments is a challenging task. The diversity of these environments and the associated plurality of decision makers’ perceptions of the issue under consideration require the exploitation of a variety of meaningful knowledge visualizations and reasoning mechanism...
Article
Full-text available
Over the years a great number of different websites have emerged that offer crowd-sourcing services, which aim at taking advantage of the vast number of anonymous workers globally available to complete tasks. In this paper we review and analyze existing websites providing crowdsourcing services in an attempt to establish a framework that will allow...
Article
Full-text available
Crowdsourcing is a new form of online labor, where the process of solving a problem is approached by soliciting contributions from a large group of people. In this paper, we attempt to investigate how different incentives affect the quality of work in such contexts, by completing the same task in three different environments: in a laboratory settin...
Chapter
Based on previous work (Assimakopoulos et al. Proceedings of KICSS’2013 [5]) where we introduced HelpMe tool, a tool that automatically selects a group of people according to rules and metrics, we now introduce inconsistency between divergent ranking concerning answers during collaborative tasks among experts. In HelpMe tool, users collaboratively...
Article
Full-text available
Biomedical research becomes increasingly interdisciplinary and collaborative in nature. Researchers need to efficiently and effectively collaborate and make decisions by meaningfully assembling, mining and analyzing available large-scale volumes of complex multi-faceted data residing in different sources. In line with related research directives re...
Article
Full-text available
Biomedical research becomes increasingly multidisciplinary and collaborative in nature. At the same time, it has recently seen a vast growth in publicly and instantly available information. As the available resources become more specialized, there is a growing need for multidisciplinary collaborations between biomedical researchers to address compl...
Article
Full-text available
This paper reports on a Web 2.0 tool that aims to facilitate and augment collaboration and decision making in data-intensive and cognitively-complex biomedical settings. The proposed tool exploits prominent high-performance computing paradigms and large data processing technologies to meaningfully search, analyze and aggregate data existing in dive...
Article
Full-text available
This paper presents a trial study to gain insight into collaborative sensemaking behaviour. We use a generic argumentation tool to capture interaction data, which is then analyzed by exploiting collaboration-specific semantic types. A Community Behaviour Analytics Tool, CommBAT, was developed. Further studies were conducted to visualize the differe...
Article
Full-text available
Argumentation support systems currently on the Web have yet to deliver their full potential to teams striving for informed sense and decision making. Today's widely used systems such as discussion forums do not support formalization and are poorly integrated in the environment of multidisciplinary teams that collaborate in data intensive and cognit...
Conference Paper
Full-text available
Generally speaking, modern research becomes increasingly interdisciplinary and collaborative in nature. Researchers need to collaborate and make decisions by meaningfully assembling, mining and analyzing available large-scale volumes of complex multi-faceted data residing in different sources. At the same time, they need to efficiently and effectiv...
Chapter
This chapter reviews the state-of-the-art on collaboration and decision making support in contemporary settings. Related issues concerning integration technologies are also discussed. The methodologies, tools and approaches discussed in the chapter are considered with respect to the information overload and cognitive complexity dimensions. The chap...
Chapter
As broadly admitted, supporting collaboration and decision making in today’s knowledge intensive environment is far from being easy. This is because collaboration settings are often associated with ever-increasing amounts of multiple types of data, obtained from diverse sources that often have a low signal-to-noise ratio for addressing the problem...
Chapter
This chapter reports on practical lessons learned during the development of innovative collaboration and decision making support services in the context of the Dicode project. These lessons concern: (i) the methodology followed and process carried out for the development of the abovementioned Dicode services (ii) the facilitation and enhancement of...
Article
Full-text available
Based on previous work [3] where we introduced HelpMe tool, a tool that automatically selects a group of people according to rules and metrics, we now introduce inconsistency between divergent ranking concerning answers during collaborative tasks among experts. In HelpMe tool, users collaboratively create a knowledge base about a subject and evalua...
Article
Full-text available
Existing collaboration support systems cope poorly with today's working environments. Although they offer functionalities to overcome cognitive overhead, these prove to be insufficient in data-intensive situations. In this paper, we identify the main causes of cognitive complexity in contemporary collaboration support systems and present the approa...
Conference Paper
Full-text available
The term Web 2.0 focuses on: user, software development and content, which results from many users that share experiences and interests. Due to the fact that many people gather on web sites looking for a solution to their prob-lem, communities of practice (CoPs) were developed. CoPs have become im-portant places for people who seek and share experi...
Article
Full-text available
This paper deals with the "data deluge" issue in contemporary decision making settings; specifically, it reports on the development of an innovative platform that incorporates and orchestrates a set of interoperable Web services to facilitate and augment collaboration and decision making in data-intensive and cognitively-complex settings. The propo...
Conference Paper
Full-text available
Decision making processes are becoming increasingly collaborative and multi-disciplinary in nature. Aiming to augment the quality of decision making in contemporary complex settings, this paper reports on an innovative approach that offers a range of alternative - but meaningfully interrelated - visualizations of the context under consideration. Th...
Article
Full-text available
Argumentation support systems have yet to deliver their full potential to teams striving for informed sense and decision making. These systems are poorly integrated in the environment of multidisciplinary teams that collaborate in data intensive and cognitive complex settings, such as those involving DNA analysis, marketing or drug testing research...
Article
Full-text available
Argumentation has been pointed out as an important means to foster learning. However, contemporary argumentation tools only poorly support the learning dimension. This is mainly due to their emphasis on formal models, which does not align well with the learning process. This article presents CoPe_it!, an innovative web-based tool that supports coll...
Article
Full-text available
Web 2.0 technologies applications have been suggested as potential enablers for the accumulation of multidisciplinary knowledge, for instance in the biomedical field. Such applications offer new ways of creating, collaborating and sharing user-generated content online. Under this context, The authors' present an innovative Web 2.0 approach that exp...
Article
Full-text available
Biomedical researchers need to efficiently and effectively collaborate and make decisions by meaningfully assembling, mining and analyzing available large-scale volumes of complex multi-faceted data residing in different sources. Arguing that dealing with data-intensive and cognitively complex settings is not a technical problem alone, this paper r...
Conference Paper
Full-text available
Aiming to address requirements concerning integration of services in the context of "big data", this paper presents an innovative approach that (i) ensures a flexible, adaptable and scalable information and computation infrastructure, and (ii) exploits the competences of stakeholders and information workers to meaningfully confront information mana...
Conference Paper
Full-text available
Biomedical research has recently seen a vast growth in publicly and instantly available information, which are often complementary or overlapping. As the available resources become more specialized, there is a growing need for multidisciplinary collaborations between biomedical researchers to address complex research questions. We present an applic...
Conference Paper
Full-text available
This paper reports on an innovative approach that aims to reduce information management costs in dataintensive and cognitively-complex biomedical environments. Recognizing the importance of prominent high-performance computing paradigms and large data processing technologies as well as collaboration support systems to remedy data-intensive issues,...
Article
Full-text available
Web 2.0 technologies applications have been suggested as potential enablers for the accumulation of multidisciplinary knowledge, for instance in the biomedical field. Such applications offer new ways of creating, collaborating and sharing user-generated content online. Under this context, the authors' present an innovative Web 2.0 approach that exp...
Conference Paper
Full-text available
This paper presents an innovative solution to Social Media monitoring. The proposed approach builds on the synergy between machine and collective human intelligence to enhance the underlying sense-making and decision making processes. In the setting under consideration, our approach reduces the data-intensiveness and overall complexity of real-life...
Conference Paper
Full-text available
This paper highlights the need for bringing together features and functionalities from both Argumentation Support Tools and Learning Management Systems (LMSs) in order to support the trainers in the construction and implementation of argumentation learning designs. In this context, it is also proposed that sharing learning designs across argumentat...
Conference Paper
Full-text available
This paper reports on a Web 2.0 tool that aims to facilitate collaboration in data-intensive biomedical settings. The proposed tool can be viewed as an innovative workbench incorporating and orchestrating a set of interoperable services that reduce the data-intensiveness and complexity overload at critical decision points to a manageable level, thu...
Conference Paper
Full-text available
The International Workshop on Adaptive Support for Team Collaboration (ASTC 2011) [1] was held in conjunction with the International Conference on User Modeling, Adaptation, and Personalization (UMAP2011), Girona, Spain, July 15, 2011. It was organized with the aim to bring together researchers from different scientific fields and research communit...
Conference Paper
Full-text available
We present CoPe_it!, an innovative web-based tool that complies with collaborative practices to provide members of diverse communities with the appropriate means to manage individual and collective knowledge during a complex sense-making and/or decision-making session. We discuss the rationale behind the tool's development and present its features...
Chapter
Full-text available
This paper reports on a hybrid approach aiming to facilitate and augment collaboration and decision making in data-intensive and cognitively-complex settings. The proposed approach exploits and builds on the most prominent high-performance computing paradigms and large data processing technologies to meaningfully search, analyze and aggregate data...
Article
Full-text available
The management of modern production/operations function is characterised by a general consensus regarding the multi-level nature of capabilities required. These capabilities are the result of decisions and actions that constitute collaboration practice, with associated discourses at the operational, improvement and strategic levels. Although, parti...
Article
Full-text available
Sense making is at the heart of cognitively complex and data intensive decision making processes. It is often conducted in collective spaces through exchange of ideas, discussions, analysing situations, and exploring alternatives. This position paper proposes a novel approach to facilitate collective sense making via a collaboration platform which...
Article
Full-text available
In the framework of the European Integrated Project PALETTE, the École Polytechnique Fédérale de Lausanne (EPFL) and the University of Patras are developing mediation services. These services aim at sustaining collaboration, supporting tacit and explicit knowledge management and enhancing individual and organizational learning in communities of pra...
Conference Paper
Usability is considered as a very significant factor towards the wide acceptance of software applications. Although the usability evaluation can take place in different forms, the entire evaluation procedure usually follows predefined ways according to a classification of the common characteristics of software applications. However, contemporary We...
Article
Manolis Tzagarakis is a Lecturer at the University of Patras, Greece and a researcher at the Computer Technology Institute. He holds a diploma from the Department of Computer Engineering and Informatics of the University of Patras, and a Ph.D. from the same university. His research interests includes hypermedia, structural computing, Web-technologi...
Article
Manolis Tzagarakis is a Lecturer at the University of Patras, Greece and a researcher at the Computer Technology Institute. He holds a diploma from the Department of Computer Engineering and Informatics of the University of Patras, and a Ph.D. from the same university. His research interests includes hypermedia, structural computing, Web-technologi...
Chapter
Collaboration tools can be exploited as virtual spaces that satisfy the community members’ needs to construct and refine their ideas, opinions, and thoughts in meaningful ways, in order to suc-cessfully assist individual and community learning. More specifically, collaboration tools when properly personalized can aid individuals to articulate their...
Chapter
Full-text available
Arguing that a vvaryying levvel of formmalityy needs to be offered in syystemms supporting argummentativvecollaboration, this article proposes an incremmental formmalization approach that has been adopted in the devvelopmment of CoPe_it!, a Web-based tool that commplies with collaborativve principles and practices, andprovvides mmemmbers of commmmu...
Chapter
Much research has been performed on how computer-based technologies might facilitate awareness among cooperating actors. However, existing approaches in providing awareness services prove to be inadequate in data-intensive instances of argumentative collaboration. Moreover, they fail to address the needs of dynamic, Web-based communities. In this c...
Chapter
In this article, we demonstrate how CoPe_it! – a web-based argumentative collaboration support tool – enables one to manage cognitively-complex collaboration settings, that is settings characterized by big volumes of interrelated data obtained from diverse sources and knowledge expressed by diverse participants. The CoPe_it! approach focuses on iss...
Chapter
Collaboration is considered as an essential element for effective learning since it enables learners to better develop their points of view and refine their knowledge. Our aim being to facilitate communities of practice members as learners, we argue that collaboration tools should provide personalization features and functionalities in order to fit...
Chapter
Arguing that a vvaryying levvel of formmalityy needs to be offered in syystemms supporting argummentativvecollaboration, this article proposes an incremmental formmalization approach that has been adopted in the devvelopmment of CoPe_it!, a Web-based tool that commplies with collaborativve principles and practices, andprovvides mmemmbers of commmmu...
Chapter
Much research has been performed on how computer-based technologies might facilitate awareness among cooperating actors. However, existing approaches in providing awareness services prove to be inadequate in data-intensive instances of argumentative collaboration. Moreover, they fail to address the needs of dynamic, web-based communities. In this c...
Chapter
Collaboration tools can be exploited as virtual spaces that satisfy the community members’ needs to construct and refine their ideas, opinions, and thoughts in meaningful ways, in order to suc-cessfully assist individual and community learning. More specifically, collaboration tools when properly personalized can aid individuals to articulate their...
Article
Full-text available
Arguing that a varying level of formality needs to be offered in systems supporting argumentative collaboration, this paper proposes an incremental formalization approach that has been adopted in the development of CoPe_it!, a web-based tool that complies with collaborative principles and practices, and provides members of communities engaged in ar...
Conference Paper
Full-text available
Advanced argumentative collaboration support systems can rarely be found in today’s World Wide Web. This can be partially justified by the fact that the current Web environment - its users and available data - differs significantly from the environments in which these systems were traditionally developed and used. Efforts to bring such systems to t...
Article
Full-text available
Web applications make increasingly use of services that are provided by external information systems to deliver advanced functionalities to end users. However, many issues regarding how these services are integrated into web applications and how service oriented web applications evolve, are reengineered and refactored are still addressed in an ad h...
Article
Full-text available
CoPe-it! is an innovative Web-based tool that complies with collaborative practices to provide members of communities with the appropriate means to manage individual and collective knowledge during a sense-making and/or decision-making session. In this article, we demonstrate its applicability in tackling cognitively-complex collaboration settings,...
Conference Paper
Full-text available
This paper presents CoPe_it!, an innovative web-based tool that supports collaboration and augments learning among members of diverse communities. The tool fosters the means to manage individual and collective knowledge during a sense-making or a decision-making session. We demonstrate its applicability for Communities of Practice (CoPs) by examini...
Article
Full-text available
Current tools aiming at supporting argumentative collaboration either provide means to successfully tame wicked problems or offer advanced reasoning mechanisms to support decision making. When CoPs need both kinds of functionalities for addressing issues this gap perplexes the process. We argue that a key factor in enabling the bridging of this gap...
Article
Full-text available
Advanced argumentation support systems can rarely be found in today's World Wide Web. One reason for this situation is the fact that the Web environment - its users and available data- differs significantly from the environments in which these systems were traditionally developed and used. Efforts to bring argumentation systems to the Web must care...
Article
Collaboration tools can be exploited as virtual spaces that satisfy the community members' needs to construct and refine their ideas, opinions, and thoughts in meaningful ways, in order to suc-cessfully assist individual and community learning. More specifically, collaboration tools when properly personalized can aid individuals to articulate their...
Article
Full-text available
Providing the necessary means to support and foster argumentative collaboration is essential for Communities of Practice to achieve their goals. However, current tools are unable to cope with the evolving stages of the collaboration. This is primarily due to the inflexible level of formality they provide. Arguing that a varying level of formality n...
Chapter
Full-text available
Arguing that a vvaryying levvel of formmalityy needs to be offered in syystemms supporting argummentativve collaboration, this article proposes an incremmental formmalization approach that has been adopted in the devvelopmment of CoPe_it!, a Web-based tool that commplies with collaborativve principles and practices, and provvides mmemmbers of commm...
Chapter
Arguing that a vvaryying levvel of formmalityy needs to be offered in syystemms supporting argummentativve collaboration, this article proposes an incremmental formmalization approach that has been adopted in the devvelopmment of CoPe_it!, a Web-based tool that commplies with collaborativve principles and practices, and provvides mmemmbers of commm...
Article
Much research has been performed on how computer-based technologies might facilitate awareness among cooperating actors. However, existing approaches in providing awareness services prove to be inadequate in data-intensive instances of argumentative collaboration. Moreover, they fail to address the needs of dynamic, Web-based communities. In this c...
Article
The analogy of a semantic network to hypertext has long been recognized, and a semantic network has been considered as a logical model of hypertext - especially for those hypertexts with typed nodes and links. Moreover, wordnets form the most representative type of semantic networks in the field of Natural Language Processing and semantics in parti...
Conference Paper
Much research has been performed on how computer-based technologies might facilitate awareness among cooperating actors. However, existing approaches in providing awareness services prove to be inadequate in data-intensive situations. Moreover, they fail to address the needs of dynamic, web-based communities. In this context, this paper presents a...