Behaviour modelling with data obtained from the Internet and contributions to cluster validation

[EN]This PhD thesis makes contributions in modelling behaviours found in different types of data acquired from the Internet and in the field of clustering evaluation. Two different types of Internet data were processed, on the one hand, internet traffic with the objective of attack detection and on the other hand, web surfing activity with the objective of web personalization, both data being of sequential nature. To this aim, machine learning techniques were applied, mostly unsupervised techniques. Moreover, contributions were made in cluster evaluation, in order to make easier the selection of the best partition in clustering problems. With regard to network attack detection, first, gureKDDCup database was generated which adds payload data to KDDCup99 connection attributes because it is essential to detect non-flood attacks. Then, by modelling this data a network Intrusion Detection System (nIDS) was proposed where context-independent payload processing was done obtaining satisfying detection rates. In the web mining context web surfing activity was modelled for web personalization. In this context, generic and non-invasive systems to extract knowledge were proposed just using the information stored in webserver log files. Contributions were done in two senses: in problem detection and in link suggestion. In the first application a meaningful list of navigation attributes was proposed for each user session to group and detect different navigation profiles. In the latter, a general and non-invasive link suggestion system was proposed which was evaluated with satisfactory results in a link prediction context. With regard to the analysis of Cluster Validity Indices (CVI), the most extensive CVI comparison found up to a moment was carried out using a partition similarity measure based evaluation methodology. Moreover, we analysed the behaviour of CVIs in a real web mining application with elevated number of clusters in which they tend to be unstable. We proposed a procedure which automatically selects the best partition analysing the slope of different CVI values.[EU]Doktorego-tesi honek internetetik eskuratutako datu mota ezberdinetan aurkitutako portaeren modelugintzan eta multzokatzeen ebaluazioan egiten ditu bere ekarpenak. Zehazki, bi mota ezberdinetako interneteko datuak prozesatu dira: batetik, interneteko trafikoa, erasoak hautemateko helburuarekin; eta bestetik, web nabigazioen jarduera, weba pertsonalizatzeko helburuarekin; bi datu motak izaera sekuentzialekoak direlarik. Helburu hauek lortzeko, ikasketa automatikoko teknikak aplikatu dira, nagusiki gainbegiratu-gabeko teknikak. Testuinguru honetan, multzokatzeen partizio onenaren aukeraketak dakartzan arazoak gutxitzeko multzokatzeen ebaluazioan ere ekarpenak egin dira. Sareko erasoen hautemateari dagokionez, lehenik gureKDDCup datubasea eratu da KDDCup99-ko konexio atributuei payload-ak (sareko paketeen datu eremuak) gehituz, izan ere, ez-flood erasoak (pakete gutxi erabiltzen dituzten erasoak) hautemateko ezinbestekoak baitira. Ondoren, datu hauek modelatuz testuinguruarekiko independenteak diren payload prozesaketak oinarri dituen sareko erasoak hautemateko sistema (network Intrusion Detection System (nIDS)) bat proposatu da maila oneko eraso hautemate-tasak lortuz. Web meatzaritzaren testuinguruan, weba pertsonalizatzeko helburuarekin web nabigazioen jarduera modelatu da. Honetarako, web zerbizarietako lorratz fitxategietan metatutako informazioa soilik erabiliz ezagutza erabilgarria erauziko duen sistema orokor eta ez-inbasiboak proposatu dira. Ekarpenak bi zentzutan eginaz: arazoen hautematean eta esteken iradokitzean. Lehen aplikazioan sesioen nabigazioa adierazteko atributu esanguratsuen zerrenda bat proposatu da, gero nabigazioak multzokatu eta nabigazio profil ezberdinak hautemateko. Bigarren aplikazioan, estekak iradokitzeko sistema orokor eta ez-inbasibo bat proposatu da, eta berau, estekak aurresateko testuinguruan ebaluatu da emaitza onak lortuz. Multzokatzeak balioztatzeko indizeen (Cluster Validity Indices (CVI)) azterketari dagokionez, gaurdaino aurkitu den CVI-en konparaketa zabalena burutu da partizioen antzekotasun neurrian oinarritutako ebaluazio metodologia erabiliz. Gainera, CVI-en portaera aztertu da egiazko web meatzaritza aplikazio batean normalean baino multzo kopuru handiagoak dituena, non CVI-ek ezegonkorrak izateko joera baitute. Arazo honi aurre eginaz, CVI ezberdinek partizio ezberdinetarako lortzen dituzten balioen maldak aztertuz automatikoki partiziorik onena hautatzen duen prozedura proposatu da.[ES]Esta tesis doctoral hace contribuciones en el modelado de comportamientos encontrados en diferentes tipos de datos adquiridos desde internet y en el campo de la evaluación del clustering. Dos tipos de datos de internet han sido procesados: en primer lugar el tráfico de internet con el objetivo de detectar ataques; y en segundo lugar la actividad generada por los usuarios web con el objetivo de personalizar la web; siendo los dos tipos de datos de naturaleza secuencial. Para este fin, se han aplicado técnicas de aprendizaje automático, principalmente técnicas no-supervisadas. Además, se han hecho aportaciones en la evaluación de particiones de clusters para facilitar la selección de la mejor partición de clusters. Respecto a la detección de ataques en la red, primero, se generó la base de datos gureKDDCup que añade el payload (la parte de contenido de los paquetes de la red) a los atributos de la conexión de KDDCup99 porque el payload es esencial para la detección de ataques no-flood (ataques que utilizan pocos paquetes). Después, se propuso un sistema de detección de intrusos (network Intrusion Detection System (IDS)) modelando los datos de gureKDDCup donde se propusieron varios preprocesos del payload independientes del contexto obteniendo resultados satisfactorios. En el contexto de la minerı́a web, se ha modelado la actividad de la navegación web para la personalización web. En este contexto se propondrán sistemas genéricos y no-invasivos para la extracción del conocimiento, utilizando únicamente la información almacenada en los ficheros log de los servidores web. Se han hecho aportaciones en dos sentidos: en la detección de problemas y en la sugerencia de links. En la primera aplicación, se propuso una lista de atributos significativos para representar las sesiones de navegación web para después agruparlos y detectar diferentes perfiles de navegación. En la segunda aplicación, se propuso un sistema general y no-invasivo para sugerir links y se evaluó en el contexto de predicción de links con resultados satisfactorios. Respecto al análisis de ı́ndices de validación de clusters (Cluster Validity Indices (CVI)), se ha realizado la más amplia comparación encontrada hasta el momento que utiliza la metodologı́a de evaluación basada en medidas de similitud de particiones. Además, se ha analizado el comportamiento de los CVIs en una aplicación real de minerı́a web con un número elevado de clusters, contexto en el que los CVIs tienden a ser inestables, ası́ que se propuso un procedimiento para la selección automática de la mejor partición en base a la pendiente de los valores de diferentes CVIs.Grant of the Basque Government (ref.: BFI08.226); Grant of Ministry of Economy and Competitiveness of the Spanish Government (ref.: BES-2011-045989); Research stay grant of Spanish Ministry of Economy and Competitiveness (ref.: EEBB-I-14-08862); University of the Basque Country UPV/EHU (BAILab, grant UFI11/45); Department of Education, Universities and Research of the Basque Government (grant IT-395-10); Ministry of Economy and Competitiveness of the Spanish Government and by the European Regional Development Fund - ERDF (eGovernAbility, grant TIN2014-52665-C2-1-R)

Detecting user demographics in twitter to inform health trends in social media

The widespread and popular use of social media and social networking applications offer a promising opportunity for gaining knowledge and insights regarding population health conditions thanks to the diversity and abundance of online user-generated information (UGHI) relating to healthcare and well-being. However, users on social media and social networking sites often do not supply their complete demographic information, which greatly undermines the value of the aforementioned information for health 2.0 research, e.g., for discerning disparities across population groups in certain health conditions. To recover the missing user demographic information, existing methods observe a limited scope of user behaviors, such as word frequencies exhibited in a user’s messages, leading to sub-optimal results. To address the above limitation and improve the performance of inferring missing user demographic information for health 2.0 research, this work proposes a new algorithmic method for extracting a social media user’s gender by exploring and exploiting a comprehensive set of a user’s behaviors on Twitter, including the user’s conversational topic choices, account profile information, and personal information. In addition, this work explores the usage of synonym expansion for detecting social media users’ ethnicities. To better capture a user’s conversational topic choices using standardized hashtags for consistent comparison, this work additionally introduces a new method that automatically generates standardized hashtags for tweets. Even though Twitter is selected as the experimental platform in this study due to its leading position among today’s social networking sites, the proposed method is in principle generically applicable to other social media sites and applications as long as there is a way to access user-generated content on those platforms. When comparing the multi-perspective learning method with the state-of-the-art approaches for gender classification, a gender classification accuracy is observed of 88.6% for the proposed approach compared with 63.4% performance for bag-of-words and 61.4% for the peer method. Additionally, the topical approach introduced in this work outperforms vocabulary-based approach with a smaller dimensionality at 69.4% accuracy. Furthermore, observable usage patterns of the cancer terms are analyzed across the ethnic groups inferred by the proposed algorithmic approaches. Variations among demographic groups are seen in the frequency of term usage during months known to be labeled as cancer awareness months. This work introduces methods that have the potential to serve as a very powerful and important tool in disseminating critical prevention, screening, and treatment messages to the community in real time. Study findings highlight the potential benefits of social media as a tool for detecting demographic differences in cancer-related discussions on social media