Nikos Korfiatis | University of East Anglia (original) (raw)

Papers by Nikos Korfiatis

New Review of Information Networking, 2012

ABSTRACT Psychologists are an understudied population in terms of information needs and informati... more ABSTRACT Psychologists are an understudied population in terms of information needs and information seeking behavior. This article provides theoretical analysis accompanied with some empirical evidence drawn from a nationwide survey of psychologists working in the Greek National Healthcare System GNHS. The empirical study was conducted during the spring of 2011, through a specially designed questionnaire distributed to all psychologists within GNHS. Psychologists seek information for patient consultation purposes and for knowledge updating; they prefer using their personal library, internet search engines, and their colleagues as information sources, while the main obstacles they face include the lack of hospital libraries. This research identified the need to more strongly link hospital library services to health psychologists on the grounds of their information needs and behaviors.

Lecture Notes in Computer Science, 2013

With the continuous increase of online services as well as energy costs, energy consumption becom... more With the continuous increase of online services as well as energy costs, energy consumption becomes a significant cost factor for the evaluation of data center operations. A significant contributor to that is the performance of database servers which are found to constitute the backbone of online services. From a software approach, while a set of novel data management technologies appear in the market e.g. key-value based or in-memory databases, classic relational database management systems (RDBMS) are still widely used. In addition from a hardware perspective, the majority of database servers is still using standard magnetic hard drives (HDDs) instead of solid state drives (SSDs) due to lower cost of storage per gigabyte, disregarding the performance boost that might be given due to high cost. In this study we focus on a software based assessment of the energy consumption of a database server by running three different and complete database workloads namely TCP-H, Star Schema Benchmark -SSB as well a modified benchmark we have derived for this study called W22. We profile the energy distribution among the most important server components and by using different resource allocation we assess the energy consumption of a typical open source RDBMS (PostgreSQL) on a standard server in relation with its performance (measured by query time). Results confirm the well-known fact that even for complete workloads, optimization of the RDBMS results to lower energy consumption.

With the continuous increase of online services as well as energy costs, energy consumption becom... more With the continuous increase of online services as well as energy costs, energy consumption becomes a significant cost factor for the evaluation of data center operations. A significant contributor to that is the performance of database servers which are found to constitute the backbone of online services. From a software approach, while a set of novel data management technologies appear in the market e.g. key-value based or in-memory databases, classic relational database management systems (RDBMS) are still widely used. In addition from a hardware perspective, the majority of database servers is still using standard magnetic hard drives (HDDs) instead of solid state drives (SSDs) due to lower cost of storage per gigabyte, disregarding the performance boost that might be given due to high cost. In this study we focus on a software based assessment of the energy consumption of a database server by running three different and complete database workloads namely TCP-H, Star Schema Benc...

Journal of the Association for Information Science and Technology, 2015

This paper aims to present a systematic literature review of research in music information seekin... more This paper aims to present a systematic literature review of research in music information seeking and its application to musical creativity and creative activities and in particular composition, performance and improvisation, and listening and analysis. A seed set of 901 articles published between 1973 and 2015 was evaluated and in total 65 studies were considered for further analyses. Data extraction and synthesis was performed through content analysis using the PRISMA method. Three thematic categories were identified in regard to music information needs: (a) those related to scholarly activities, (b) musically motivated, as well as (c) those which are related to socializing and communication. In addition, 3 categories of music information sources were connected to musical creativity: (i) those that are related to Internet and media technologies, (ii) those that are related to music libraries, organizations, and music stores, and (iii) those that are related to the subjects' social settings. The paper provides a systematic review, with the aim of showcasing the effect of modern information retrieval techniques in a creative and intensive area of information-dependent activity such as music making and consumption.

SSRN Electronic Journal, 2000

ABSTRACT Government regulation of the clinical practice is a characteristic aspect of the medical... more ABSTRACT Government regulation of the clinical practice is a characteristic aspect of the medical profession. Regardless of whether this regulation derives from government sourced guidelines or materials from government-sponsored institutions, it results to a high production of information resources (institutional information resources) which are disseminated to the clinical stuff in order to ensure compliance. In that case the issue of credibility of this information resources might arise since medical practice is characterized by a high frequency of change. The later involves continuous effort by the clinical staff which is motivated by work related factors (e.g. need of compliance) or personal motivation (need for self-improvement). In this study we consider a simple trust model for an information resource where we assume that perceived trust is a direct antecedent of perceived credibility. We evaluate whether work-related or personal motivated factors influence the relation between perceived credibility and trust towards institutional information sources and how the effect of each factor affects this relation. Findings suggest that work-related factors have higher impact on the relation between credibility and trust than personal motivation factors while at the same time are stressing the important role of hospital libraries as a dissemination point for government-sponsored information resources.

SSRN Electronic Journal, 2000

ABSTRACT Online product reviews are an important resource for consumers in online marketplaces be... more ABSTRACT Online product reviews are an important resource for consumers in online marketplaces because they provide a useful source of support information during the purchase of goods. Furthermore, in some online marketplaces consumers have the opportunity to evaluate the usefulness of a review by using a binary evaluation interface provided by the online marketplace. These evaluations produce a usefulness score, which is calculated as a fraction of helpful votes out of the total votes that a review has received. The results of these evaluations indicate that the usefulness score of a particular review is significantly affected by the qualitative characteristics of the review as measured by readability tests applied to a large dataset of reviews collected from the United Kingdom section of the popular online marketplace Amazon.

The well-known 3V architectural paradigm for Big Data introduced by Laney (2011) provides a simpl... more The well-known 3V architectural paradigm for Big Data introduced by Laney (2011) provides a simplified framework for defining the architecture of a big data platform to be deployed in various scenarios tackling processing of massive datasets. While additional components such as Variability and Veracity have been discussed as an extension to the 3V model, the basic components (Volume, Variety, and Velocity) provide a quantitative framework while variability and veracity target a more qualitative approach. In this paper we argue why the basic 3V's are not equal due to the different requirements that need to be covered in case there exist higher demands for a particular "V". We call this paradigm heterogeneity and we provide a taxonomy of the existing tools (as of 2013) covering the Hadoop ecosystem from that perspective. This paper contributes on the understanding of the Hadoop ecosystem from both an architectural and requirements viewpoint and aims to help researchers and practitioners on the design of scalable platforms targeting different business scenarios.

SSRN Electronic Journal, 2000

ABSTRACT Helpfulness prediction of online consumer reviews is an interesting research topic with ... more ABSTRACT Helpfulness prediction of online consumer reviews is an interesting research topic with immediate practical applications both from a data mining and marketing perspective. As such a set of studies have been published in the last few years to tackle this problem, targeting the reviews' textual characteristics. In this paper, we propose and evaluate two text-based features that have not been used in the context of consumer review helpfulness prediction before. The first considers a variation of the bigram feature, utilizing grammatical dependencies instead of word adjacency. The second captures the type and amount of discourse in a text by looking for discourse connectives. In our experiments, we treat the helpfulness prediction problem as a binary classification task. The results show that both features contain valuable information for evaluating review helpfulness, however they should be used with caution due to the restrictive experimental setup. The study serves as a ground for future work regarding the usefulness of the proposed features in that perspective.

SSRN Electronic Journal, 2000

ABSTRACT Online consumer reviews constitute an integral aspect of electronic transactions as they... more ABSTRACT Online consumer reviews constitute an integral aspect of electronic transactions as they play a part in lowering customer uncertainty during purchase decision making. This paper studies the aspect of negativity exhibited on the justification of its valence by the review text (as a dependent variable) and the influence of product price and product type to either an experience or a search good and across the values of the review rating scale on a dataset consisting of N=667 products with a minimum number of 15 reviews per product. The study uses novel opinion mining methodology based on a phrase-based opinion list that has been extracted from a large corpus of online consumer reviews gathered from the German site of Amazon (Amazon.de). The study also provides (1) empirical evidence that product type (experience or search good) affects review text negativity, with experience goods receiving higher amounts of negative text in relation with search goods and (2) that higher product price results to fewer negative statements in the review text. The paper also provides discussion of the findings and practical implications in relation with the IS literature.

SSRN Electronic Journal, 2000

ABSTRACT This paper examines gender effects reported in a quasi-experimental implementation of a ... more ABSTRACT This paper examines gender effects reported in a quasi-experimental implementation of a social dilemma using Facebook profile owners as subjects. By sending personal invitations via Facebook interest groups, we were able to recruit a fairly large number of participants (N=216) who participated in a “one-shot” variation of the Voluntary Contribution Mechanism (VCM). In addition to participating in the social dilemma, participants provided information about their online profile and their attitude towards Facebook. We observed gender effects on the cooperation style of participants who use Facebook frequently in order to communicate not only with friends and family but also with work colleagues and business acquaintances.

SSRN Electronic Journal, 2000

ABSTRACT Yahoo!Answers operates a question-answering community of users who post questions and re... more ABSTRACT Yahoo!Answers operates a question-answering community of users who post questions and receive answers on various topics. In this paper we examine the effect of activity on service posture (measured by volume and time) as expressed by user contributed effort and user received benefit in an online community facilitated by members of the Yahoo!Answers community. By programming a web crawler to store a random sample of questions posted over a period of one month we used a set of time series, random effects and logistic regression models which confirm to a large extend our formed hypotheses. Findings indicate that the ratio of contributed effort and received benefit has an effect on service posture (volume and time). In particular we find that users who contribute more effort in the community than received benefit get a question answered by more users in less time than users who receive more benefit than the effort they contribute to the community.

SSRN Electronic Journal, 2000

New Review of Information Networking, 2012

ABSTRACT Psychologists are an understudied population in terms of information needs and informati... more ABSTRACT Psychologists are an understudied population in terms of information needs and information seeking behavior. This article provides theoretical analysis accompanied with some empirical evidence drawn from a nationwide survey of psychologists working in the Greek National Healthcare System GNHS. The empirical study was conducted during the spring of 2011, through a specially designed questionnaire distributed to all psychologists within GNHS. Psychologists seek information for patient consultation purposes and for knowledge updating; they prefer using their personal library, internet search engines, and their colleagues as information sources, while the main obstacles they face include the lack of hospital libraries. This research identified the need to more strongly link hospital library services to health psychologists on the grounds of their information needs and behaviors.

Library & Information Science Research, 2012

ABSTRACT A measure for the assessment of resource use in information services provides an applica... more ABSTRACT A measure for the assessment of resource use in information services provides an application within the information services area of the long tail concept. The analysis quantifies the long tail concept and is applicable to all libraries and information services, independent of their size and circulation properties. The paradigm of the Lorenz curve and the Gini coefficient from macroeconomics is adapted in the context of information services. The Gini coefficient examines the skewness of the Lorenz curve against an ideal cumulative distribution that is represented by a 45-degree line. In this context, the Lorenz curve depicts the cumulative percentage of collection items versus the number of loans and identifies the different levels of library resource use on the part of users by measuring how close the Gini coefficient is to the unity (i.e., the Gini of the 45-degree line is identified).

Expert Systems with Applications, 2013

ABSTRACT Online consumer reviews play an important role in the decision to purchase services onli... more ABSTRACT Online consumer reviews play an important role in the decision to purchase services online, mainly due to the rich information source they provide to consumers in terms of evaluating “experience”-type products and services that can be booked using the Internet, with online travel services being a significant example. However, different types of travelers assess each quality indicator differently, depending on the type of travel they engage in, and not necessarily their cultural or age background (e.g. solo travelers, young couples with children etc.). In this study, we present architecture for a demographic recommendation system, based on a user-defined hierarchy of service quality indicator importance, and classification of traveler types. We use an algebraic approach to ascertain preferences from a large dataset that we obtained from the popular travel website Booking.com using a web crawler and compared with the customer-constructed preference matrix. Interestingly, the architecture of the evaluated recommendation system takes into account already defined demand characteristics of the hotels (such as the number of reviews of specific consumer types compared to the total number of reviews) in order to provide an example architecture for a recommendation system based on user-defined preference criteria.

In this paper we propose a middleware infrastructure to address the problem of filtering unsolici... more In this paper we propose a middleware infrastructure to address the problem of filtering unsolicitated mail messages (known as SPAM). In our approach we use Bayesian Classifications of SPAM messages built upon categorization models that map a probability to a word using text analysis not only to unsolicitated mails but also to legitimate mail messages, making easier to extract a cumulate inference about the nature of the e-mail message. Our proposed architecture is based on the extension of these models using the advances of Collaborative Filtering Methods expressed via Peer-to-peer networks will help to built more effective and accurate anti-spam filters.

The concept of microcontent poses a new set of challenges for the design of recommender systems t... more The concept of microcontent poses a new set of challenges for the design of recommender systems that can assist the users to accomplish a broad set of complex informational tasks as well as to evaluate the importance of information resources such as microcontent structures. In this paper we formulate an approach by using an adaptation of the hubs and authorities

Building on the interpersonal evaluation theory in social psychology, this study explores the exi... more Building on the interpersonal evaluation theory in social psychology, this study explores the existence of a negativity bias in evaluating the helpfulness of online reviews, i.e., whether users perceive a negative review to be more helpful than a positive review. An analysis of 7659 book reviews from Amazon.co.uk shows that a negativity bias disappears after controlling for moderating factors related to evaluation quality such as readability and length. The finding demonstrates that the negativity bias suggested by the social psychology literature is not readily applicable to consumer-generated online reviews. The study contributes to the theorization of word-of-mouth by exploring the qualitative characteristics of consumer-generated reviews in addition to their valence. The study also makes a theoretical contribution to information systems research by introducing and extending the interpersonal evaluation theory to online review research.

New Review of Information Networking, 2012

ABSTRACT Psychologists are an understudied population in terms of information needs and informati... more ABSTRACT Psychologists are an understudied population in terms of information needs and information seeking behavior. This article provides theoretical analysis accompanied with some empirical evidence drawn from a nationwide survey of psychologists working in the Greek National Healthcare System GNHS. The empirical study was conducted during the spring of 2011, through a specially designed questionnaire distributed to all psychologists within GNHS. Psychologists seek information for patient consultation purposes and for knowledge updating; they prefer using their personal library, internet search engines, and their colleagues as information sources, while the main obstacles they face include the lack of hospital libraries. This research identified the need to more strongly link hospital library services to health psychologists on the grounds of their information needs and behaviors.

Lecture Notes in Computer Science, 2013

With the continuous increase of online services as well as energy costs, energy consumption becom... more With the continuous increase of online services as well as energy costs, energy consumption becomes a significant cost factor for the evaluation of data center operations. A significant contributor to that is the performance of database servers which are found to constitute the backbone of online services. From a software approach, while a set of novel data management technologies appear in the market e.g. key-value based or in-memory databases, classic relational database management systems (RDBMS) are still widely used. In addition from a hardware perspective, the majority of database servers is still using standard magnetic hard drives (HDDs) instead of solid state drives (SSDs) due to lower cost of storage per gigabyte, disregarding the performance boost that might be given due to high cost. In this study we focus on a software based assessment of the energy consumption of a database server by running three different and complete database workloads namely TCP-H, Star Schema Benchmark -SSB as well a modified benchmark we have derived for this study called W22. We profile the energy distribution among the most important server components and by using different resource allocation we assess the energy consumption of a typical open source RDBMS (PostgreSQL) on a standard server in relation with its performance (measured by query time). Results confirm the well-known fact that even for complete workloads, optimization of the RDBMS results to lower energy consumption.

With the continuous increase of online services as well as energy costs, energy consumption becom... more With the continuous increase of online services as well as energy costs, energy consumption becomes a significant cost factor for the evaluation of data center operations. A significant contributor to that is the performance of database servers which are found to constitute the backbone of online services. From a software approach, while a set of novel data management technologies appear in the market e.g. key-value based or in-memory databases, classic relational database management systems (RDBMS) are still widely used. In addition from a hardware perspective, the majority of database servers is still using standard magnetic hard drives (HDDs) instead of solid state drives (SSDs) due to lower cost of storage per gigabyte, disregarding the performance boost that might be given due to high cost. In this study we focus on a software based assessment of the energy consumption of a database server by running three different and complete database workloads namely TCP-H, Star Schema Benc...

Journal of the Association for Information Science and Technology, 2015

This paper aims to present a systematic literature review of research in music information seekin... more This paper aims to present a systematic literature review of research in music information seeking and its application to musical creativity and creative activities and in particular composition, performance and improvisation, and listening and analysis. A seed set of 901 articles published between 1973 and 2015 was evaluated and in total 65 studies were considered for further analyses. Data extraction and synthesis was performed through content analysis using the PRISMA method. Three thematic categories were identified in regard to music information needs: (a) those related to scholarly activities, (b) musically motivated, as well as (c) those which are related to socializing and communication. In addition, 3 categories of music information sources were connected to musical creativity: (i) those that are related to Internet and media technologies, (ii) those that are related to music libraries, organizations, and music stores, and (iii) those that are related to the subjects' social settings. The paper provides a systematic review, with the aim of showcasing the effect of modern information retrieval techniques in a creative and intensive area of information-dependent activity such as music making and consumption.

SSRN Electronic Journal, 2000

ABSTRACT Government regulation of the clinical practice is a characteristic aspect of the medical... more ABSTRACT Government regulation of the clinical practice is a characteristic aspect of the medical profession. Regardless of whether this regulation derives from government sourced guidelines or materials from government-sponsored institutions, it results to a high production of information resources (institutional information resources) which are disseminated to the clinical stuff in order to ensure compliance. In that case the issue of credibility of this information resources might arise since medical practice is characterized by a high frequency of change. The later involves continuous effort by the clinical staff which is motivated by work related factors (e.g. need of compliance) or personal motivation (need for self-improvement). In this study we consider a simple trust model for an information resource where we assume that perceived trust is a direct antecedent of perceived credibility. We evaluate whether work-related or personal motivated factors influence the relation between perceived credibility and trust towards institutional information sources and how the effect of each factor affects this relation. Findings suggest that work-related factors have higher impact on the relation between credibility and trust than personal motivation factors while at the same time are stressing the important role of hospital libraries as a dissemination point for government-sponsored information resources.

SSRN Electronic Journal, 2000

ABSTRACT Online product reviews are an important resource for consumers in online marketplaces be... more ABSTRACT Online product reviews are an important resource for consumers in online marketplaces because they provide a useful source of support information during the purchase of goods. Furthermore, in some online marketplaces consumers have the opportunity to evaluate the usefulness of a review by using a binary evaluation interface provided by the online marketplace. These evaluations produce a usefulness score, which is calculated as a fraction of helpful votes out of the total votes that a review has received. The results of these evaluations indicate that the usefulness score of a particular review is significantly affected by the qualitative characteristics of the review as measured by readability tests applied to a large dataset of reviews collected from the United Kingdom section of the popular online marketplace Amazon.

The well-known 3V architectural paradigm for Big Data introduced by Laney (2011) provides a simpl... more The well-known 3V architectural paradigm for Big Data introduced by Laney (2011) provides a simplified framework for defining the architecture of a big data platform to be deployed in various scenarios tackling processing of massive datasets. While additional components such as Variability and Veracity have been discussed as an extension to the 3V model, the basic components (Volume, Variety, and Velocity) provide a quantitative framework while variability and veracity target a more qualitative approach. In this paper we argue why the basic 3V's are not equal due to the different requirements that need to be covered in case there exist higher demands for a particular "V". We call this paradigm heterogeneity and we provide a taxonomy of the existing tools (as of 2013) covering the Hadoop ecosystem from that perspective. This paper contributes on the understanding of the Hadoop ecosystem from both an architectural and requirements viewpoint and aims to help researchers and practitioners on the design of scalable platforms targeting different business scenarios.

SSRN Electronic Journal, 2000

ABSTRACT Helpfulness prediction of online consumer reviews is an interesting research topic with ... more ABSTRACT Helpfulness prediction of online consumer reviews is an interesting research topic with immediate practical applications both from a data mining and marketing perspective. As such a set of studies have been published in the last few years to tackle this problem, targeting the reviews' textual characteristics. In this paper, we propose and evaluate two text-based features that have not been used in the context of consumer review helpfulness prediction before. The first considers a variation of the bigram feature, utilizing grammatical dependencies instead of word adjacency. The second captures the type and amount of discourse in a text by looking for discourse connectives. In our experiments, we treat the helpfulness prediction problem as a binary classification task. The results show that both features contain valuable information for evaluating review helpfulness, however they should be used with caution due to the restrictive experimental setup. The study serves as a ground for future work regarding the usefulness of the proposed features in that perspective.

SSRN Electronic Journal, 2000

ABSTRACT Online consumer reviews constitute an integral aspect of electronic transactions as they... more ABSTRACT Online consumer reviews constitute an integral aspect of electronic transactions as they play a part in lowering customer uncertainty during purchase decision making. This paper studies the aspect of negativity exhibited on the justification of its valence by the review text (as a dependent variable) and the influence of product price and product type to either an experience or a search good and across the values of the review rating scale on a dataset consisting of N=667 products with a minimum number of 15 reviews per product. The study uses novel opinion mining methodology based on a phrase-based opinion list that has been extracted from a large corpus of online consumer reviews gathered from the German site of Amazon (Amazon.de). The study also provides (1) empirical evidence that product type (experience or search good) affects review text negativity, with experience goods receiving higher amounts of negative text in relation with search goods and (2) that higher product price results to fewer negative statements in the review text. The paper also provides discussion of the findings and practical implications in relation with the IS literature.

SSRN Electronic Journal, 2000

ABSTRACT This paper examines gender effects reported in a quasi-experimental implementation of a ... more ABSTRACT This paper examines gender effects reported in a quasi-experimental implementation of a social dilemma using Facebook profile owners as subjects. By sending personal invitations via Facebook interest groups, we were able to recruit a fairly large number of participants (N=216) who participated in a “one-shot” variation of the Voluntary Contribution Mechanism (VCM). In addition to participating in the social dilemma, participants provided information about their online profile and their attitude towards Facebook. We observed gender effects on the cooperation style of participants who use Facebook frequently in order to communicate not only with friends and family but also with work colleagues and business acquaintances.

SSRN Electronic Journal, 2000

ABSTRACT Yahoo!Answers operates a question-answering community of users who post questions and re... more ABSTRACT Yahoo!Answers operates a question-answering community of users who post questions and receive answers on various topics. In this paper we examine the effect of activity on service posture (measured by volume and time) as expressed by user contributed effort and user received benefit in an online community facilitated by members of the Yahoo!Answers community. By programming a web crawler to store a random sample of questions posted over a period of one month we used a set of time series, random effects and logistic regression models which confirm to a large extend our formed hypotheses. Findings indicate that the ratio of contributed effort and received benefit has an effect on service posture (volume and time). In particular we find that users who contribute more effort in the community than received benefit get a question answered by more users in less time than users who receive more benefit than the effort they contribute to the community.

SSRN Electronic Journal, 2000

New Review of Information Networking, 2012

ABSTRACT Psychologists are an understudied population in terms of information needs and informati... more ABSTRACT Psychologists are an understudied population in terms of information needs and information seeking behavior. This article provides theoretical analysis accompanied with some empirical evidence drawn from a nationwide survey of psychologists working in the Greek National Healthcare System GNHS. The empirical study was conducted during the spring of 2011, through a specially designed questionnaire distributed to all psychologists within GNHS. Psychologists seek information for patient consultation purposes and for knowledge updating; they prefer using their personal library, internet search engines, and their colleagues as information sources, while the main obstacles they face include the lack of hospital libraries. This research identified the need to more strongly link hospital library services to health psychologists on the grounds of their information needs and behaviors.

Library & Information Science Research, 2012

ABSTRACT A measure for the assessment of resource use in information services provides an applica... more ABSTRACT A measure for the assessment of resource use in information services provides an application within the information services area of the long tail concept. The analysis quantifies the long tail concept and is applicable to all libraries and information services, independent of their size and circulation properties. The paradigm of the Lorenz curve and the Gini coefficient from macroeconomics is adapted in the context of information services. The Gini coefficient examines the skewness of the Lorenz curve against an ideal cumulative distribution that is represented by a 45-degree line. In this context, the Lorenz curve depicts the cumulative percentage of collection items versus the number of loans and identifies the different levels of library resource use on the part of users by measuring how close the Gini coefficient is to the unity (i.e., the Gini of the 45-degree line is identified).

Expert Systems with Applications, 2013

ABSTRACT Online consumer reviews play an important role in the decision to purchase services onli... more ABSTRACT Online consumer reviews play an important role in the decision to purchase services online, mainly due to the rich information source they provide to consumers in terms of evaluating “experience”-type products and services that can be booked using the Internet, with online travel services being a significant example. However, different types of travelers assess each quality indicator differently, depending on the type of travel they engage in, and not necessarily their cultural or age background (e.g. solo travelers, young couples with children etc.). In this study, we present architecture for a demographic recommendation system, based on a user-defined hierarchy of service quality indicator importance, and classification of traveler types. We use an algebraic approach to ascertain preferences from a large dataset that we obtained from the popular travel website Booking.com using a web crawler and compared with the customer-constructed preference matrix. Interestingly, the architecture of the evaluated recommendation system takes into account already defined demand characteristics of the hotels (such as the number of reviews of specific consumer types compared to the total number of reviews) in order to provide an example architecture for a recommendation system based on user-defined preference criteria.

In this paper we propose a middleware infrastructure to address the problem of filtering unsolici... more In this paper we propose a middleware infrastructure to address the problem of filtering unsolicitated mail messages (known as SPAM). In our approach we use Bayesian Classifications of SPAM messages built upon categorization models that map a probability to a word using text analysis not only to unsolicitated mails but also to legitimate mail messages, making easier to extract a cumulate inference about the nature of the e-mail message. Our proposed architecture is based on the extension of these models using the advances of Collaborative Filtering Methods expressed via Peer-to-peer networks will help to built more effective and accurate anti-spam filters.

The concept of microcontent poses a new set of challenges for the design of recommender systems t... more The concept of microcontent poses a new set of challenges for the design of recommender systems that can assist the users to accomplish a broad set of complex informational tasks as well as to evaluate the importance of information resources such as microcontent structures. In this paper we formulate an approach by using an adaptation of the hubs and authorities

Building on the interpersonal evaluation theory in social psychology, this study explores the exi... more Building on the interpersonal evaluation theory in social psychology, this study explores the existence of a negativity bias in evaluating the helpfulness of online reviews, i.e., whether users perceive a negative review to be more helpful than a positive review. An analysis of 7659 book reviews from Amazon.co.uk shows that a negativity bias disappears after controlling for moderating factors related to evaluation quality such as readability and length. The finding demonstrates that the negativity bias suggested by the social psychology literature is not readily applicable to consumer-generated online reviews. The study contributes to the theorization of word-of-mouth by exploring the qualitative characteristics of consumer-generated reviews in addition to their valence. The study also makes a theoretical contribution to information systems research by introducing and extending the interpersonal evaluation theory to online review research.