This dissertation studies data privacy preservation in collaborative filtering based recommender systems and proposes several collaborative filtering models that aim at preserving user privacy from different perspectives. The empirical study on multiple classical recommendation algorithms presents the basic idea of the models and explores their performance on real world datasets. The algorithms that are investigated in this study include a popularity based model, an item similarity based model, a singular value decomposition based model, and a bipartite graph model. Top-N recommendations are evaluated to examine the prediction accuracy. It is apparent that with more customers' preference data, recommender systems can better profile customers' shopping patterns which in turn produces product recommendations with higher accuracy. The precautions should be taken to address the privacy issues that arise during data sharing between two vendors. Study shows that matrix factorization techniques are ideal choices for data privacy preservation by their nature. In this dissertation, singular value decomposition (SVD) and nonnegative matrix factorization (NMF) are adopted as the fundamental techniques for collaborative filtering to make privacy-preserving recommendations. The proposed SVD based model utilizes missing value imputation, randomization technique, and the truncated SVD to perturb the raw rating data. The NMF based models, namely iAux-NMF and iCluster-NMF, take into account the auxiliary information of users and items to help missing value imputation and privacy preservation. Additionally, these models support efficient incremental data update as well. A good number of online vendors allow people to leave their feedback on products. It is considered as users' public preferences. However, due to the connections between users' public and private preferences, if a recommender system fails to distinguish real customers from attackers, the private preferences of real customers can be exposed. This dissertation addresses an attack model in which an attacker holds real customers' partial ratings and tries to obtain their private preferences by cheating recommender systems. To resolve this problem, trustworthiness information is incorporated into NMF based collaborative filtering techniques to detect the attackers and make reasonably different recommendations to the normal users and the attackers. By doing so, users' private preferences can be effectively protected.

The use of celebrity endorsers is a popular marketing strategy in many countries. Typically, many marketers believe that using celebrities is a viable marketing strategy for attracting customers, increasing market share and improving sales for their market offerings. The celebrity endorsement strategy using local celebrities is increasing in South Africa. Many South African marketers are now using popular local black celebrities in an attempt to attract the prosperous black emerging middle class, known as Black Diamonds. Black Generation Y students offer great promise to marketers in the South African market as their tertiary education is likely to lead to higher future earning potential and subsequent entry into the already prosperous black emerging middle class segment. Given the increased use of local black celebrities and the market potential of the black Generation Y cohort in South Africa, it is important to investigate whether this marketing strategy may be effective when used in this segment. Celebrity endorsement may work effectively if the correct celebrity is chosen to promote a product but may have costly results if an inappropriate celebrity is chosen. Ohanian (1990) developed a scale to facilitate the selection of celebrity endorsers. The scale is based on the source credibility model that includes the source attractiveness, trustworthiness and expertise model. This study set out to determine whether the black Generation Y students have positive perceptions of local black celebrity endorsers using the celebrity endorsers‟ credibility scale developed by Ohanian (1990). Furthermore, the scale was validated using confirmatory factor analysis and structural equation modelling in order to ascertain whether the scale remains applicable when used in the South African context. A non-probability convenience sample of 880 (440 per institution) black students aged between 18 and 24 years was taken in 2012 from the two registered public higher education institutions in the Gauteng province of South Africa. Following a top-of-the-mind-awareness test, four local black celebrities were identified, namely Connie Ferguson, Black Coffee, DJ Sbu and Zahara. In a second top-of-the-mind-awareness test to determine which product types each celebrity is considered to most suitable to endorse, Connie Ferguson was linked to cosmetics, Black Coffee to hot beverages, DJ Sbu to men’s clothing and Zahara to traditional African clothes and jewellery. The relevant primary data was collected using a self-administered questionnaire that had four versions – one per identified celebrity. Lecturers at the two public HEIs were contacted and asked if they would distribute the questionnaires (four versions) to their students to complete during lecture periods. The questionnaires were hand delivered to the relevant lecturers and those completed were immediately collected. The questionnaire requested respondents to indicate on a six-point Likert scale their perceptions of the four selected celebrities‟ attractiveness, trustworthiness and expertise in endorsing their selected product types. In addition, respondents were asked to provide certain demographic data. Findings from the study indicated that black Generation Y students have positive perceptions of the selected local black celebrity endorsers‟ attractiveness, trustworthiness and expertise in endorsing their selected product types. In addition, the results of both the confirmatory factor analysis and the structural equation modelling suggest that the scale developed by Ohanian (1990) to be a valid measure for selecting celebrity endorsers when applied in South Africa. Insights gained from this study will assist both marketing academics and practitioners understand the perceptions of the black Generation Y students towards the use of local black celebrities in product promotions in the South African market. / MCom, Marketing Management, North-West University, Vaal Triangle Campus, 2013

The ability to establish and maintain trust is regarded as a critical modern leadership skill. However, different conceptualisations of trust saw to it that the empirical and theoretical sides of research did not merge. As a result, trust has been studied in a variety of different ways and resulted in a varied and fragmented knowledge base, which this study attempts to address. The objectives of this study were to investigate conceptualizations of trust as perceived by middle- and senior level managers in a military medical basis in order to provide recommendations to management on how to build trust. Research was conducted in two phases of investigation. In phase 1 a literature review of the concept was conducted by analyzing and categorizing definitions and frameworks currently in use. In the second phase an empirical investigation was conducted by means of a descriptive and explorative qualitative research design and the use of a non-probability purposive sampling technique. The results showed that three proposed factors of trustworthiness (ability, benevolence and integrity), effective communication as well as perceived justice and fairness are fundamental to the establishment of trust. It is evident that management should draft a strategic plan to ensure that trust is established and maintained on a sustainable basis. The findings will contribute to a better understanding of the essential nature of trust and assist management in an effective approach to master trust as an essential leadership skill in order to successfully enhance business reputation and outcomes. / Thesis (MBA)--North-West University, Potchefstroom Campus, 2011

The ability to establish and maintain trust is regarded as a critical modern leadership skill. However, different conceptualisations of trust saw to it that the empirical and theoretical sides of research did not merge. As a result, trust has been studied in a variety of different ways and resulted in a varied and fragmented knowledge base, which this study attempts to address. The objectives of this study were to investigate conceptualizations of trust as perceived by middle- and senior level managers in a military medical basis in order to provide recommendations to management on how to build trust. Research was conducted in two phases of investigation. In phase 1 a literature review of the concept was conducted by analyzing and categorizing definitions and frameworks currently in use. In the second phase an empirical investigation was conducted by means of a descriptive and explorative qualitative research design and the use of a non-probability purposive sampling technique. The results showed that three proposed factors of trustworthiness (ability, benevolence and integrity), effective communication as well as perceived justice and fairness are fundamental to the establishment of trust. It is evident that management should draft a strategic plan to ensure that trust is established and maintained on a sustainable basis. The findings will contribute to a better understanding of the essential nature of trust and assist management in an effective approach to master trust as an essential leadership skill in order to successfully enhance business reputation and outcomes. / Thesis (MBA)--North-West University, Potchefstroom Campus, 2011

Based around a case study of the traditional toy industry, the research examines how companies create trust with parents, the main toy purchasers, and the importance of ethical behaviour in trust development when a vulnerable community is involved. Previous literature has revealed that trust leads to mutually beneficial company-consumer relationships but scholars have failed to agree on its definition, dimensions or measurement due to its complexity, diversity and intangibility. Few have distinguished between 'trustworthiness' as a moral quality of organisations and 'trust', which is a consumer judgement about companies and brands, made as part of their purchase deliberations. A review of the literature led to the development of a framework of trustworthy behaviour identifying five sets of antecedents (organisational, individual, control, relational and branding factors) and four key dimensions with related variables - 'Integrity' and 'Benevolence', relating to ethical constructs and 'Commitment' and 'Satisfaction', relating to organisational constructs. The model was then substantiated through qualitative research with a sample of senior managers in 12 leading toy companies and other stakeholders including industry body representatives, retailers and parents. The findings revealed that in a challenging economic climate, trust in toy companies is being driven principally by the marketing offer and by external influencers such as legislators, retailers, licensors, and the media. Examples of good ethical practices were identified, although often unnoticed by consumers, and the worthier companies, for whom trustworthiness was important, appeared to be faring less well economically than companies selling third party brands. Consumers' trust was significant in the preschool market but diminished in importance as children matured when their influence overrode parents' more rational purchase considerations. The research revealed a paradox that parents as well as children are vulnerable consumers who are often bypassed in the marketing process. Whatever children's consumer rights, there will always be a lack of trust in the industry whilst young children rather than parents are so blatantly targeted.

E-privacy concerns are among the online transactions risks that influence the use of e-services and e-government services. Whilst there have been studies that have analysed the impact of e-privacy on the willingness of people to utilize the Internet, especially in e-commerce, there has been limited research in relation to e-government services for a specific demographic group. This study has examined the impact of e-privacy risk concerns on the acceptance of e-government services in Oman using an integrated model. The model is based on Liu et al.‟s (2005) privacy-trust-behavioral intention model, the broader technology acceptance literature, and recent work on e-privacy awareness and protection. The research used both quantitative and qualitative approaches: data collection by questionnaire and a series of semi-structured interviews. The sampling frame for the study was civil services government employees in Oman. The model was tested using partial least squares and the results were compared to those obtained from the interview data. The study found that e-privacy awareness significantly impacts the level of e-privacy risk concerns. Social norms and perceived usefulness were found to play a significant role in influencing the intention to use e-government services. The study also found that e-privacy concerns and perceptions of the protection available against risks influence citizens‟ intentions to use e-government services via their influence on the perceived trustworthiness of these services. Thus trustworthiness is a factor that could be an obstacle to successful e-government services project implementation. Therefore the thesis recommends that governments pay greater attention to the role of e-privacy concerns and put in place security and e-privacy controls. Citizens should then be made aware of these in order to build the required level of trust and confidence in these services.

Thesis (MPhil)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: This thesis uses narrative analysis to explore the ways by which consultants seek to improve their perceived trustworthiness in initial client-consultant interactions. It is argued that consultants rely on identity-based trust perceptions by the clients and that this basis for trust can be favourably presented, within certain constraints, through narrative positioning. This narrative positioning, in the service of identity construction, is called identity positioning in the thesis. The thesis is situated in the literature on management consulting aimed at micro-level high-contact client-consultant interactions. These kinds of interactions trade on trust and identity. The various bases for trust are described, namely identity, structural, and dispositional based trust. Amongst these three bases, identity trust is highlighted as the most dominant in the context of clientconsultant interactions, especially in initial interactions where the consultant is unknown to the participants. It is to be expected in initial interactions that there will be a lot of scope for identity construction. A framework is then developed to relate identity construction and trust, which can be used as the basis for narrative positioning analysis. The framework consists of two dimensions along which identities can be positioned: social obligations and relational positioning latitude. It is argued that dispositional trust relates to relational positioning latitude, whereas structural bases of trust relates to social obligations. Identity based trust therefore indicates where the consultant fits within the structural or dispositional bases of trust. It is then shown how context moderates which of the trust bases will be dominant, and how this might manifest in the narrative of the consultant. It provides three general contexts, each leading to the emergence of a particular dominant basis for trustworthiness perceptions by the clients. The particular case analysed in this thesis correlates to a specific contexts within the framework. This context is where the consultant is unknown. The last part of the thesis illustrates the use of the framework and context as it guides the analysis of a particular consultant’s personal narrative during an initial interaction with clients. The analysis is then repeated for the consultant's software product narrative. The structures of the two narratives are then compared to show how the consultant also attempted to extend the identity-based trust to his software product. / AFRIKAANSE OPSOMMING: Hierdie tesis maak gebruik van narratiewe analise om die maniere te verken waarop konsultante die persepsies van hul betroubaarheid probeer verbeter in die aanvang fase van kliënt-konsultant interaksies. Daar word aangevoer dat konsultante staatmaak op identiteit-gebaseerde vertroue persepsies deur die kliënte en dat dié basis van vertroue gunstig aangebied kan word, binne sekere beperkings, deur middel van narratiewe posisionering. Hierdie narratiewe plasing, wat in die diens van die konstruksie van identiteit is, word identiteit posisionering genoem in die tesis. Die tesis is geleë in die literatuur oor bestuurs konsultering met die oogmerk op mikrovlak hoëkontak kliënt-konsultant interaksies. Hierdie soort interaksies handel in vertroue en identiteit. Die verskillende basisse vir vertroue word beskryf, naamlik identiteit, strukturele, en disposisionele gebaseerde vertroue. Onder hierdie drie basisse, word identiteit gebaseerde vertroue as die mees dominante in die konteks van die kliënt-konsultant interaksies uitgelig, veral in die eerste interaksies waar die konsultant onbekend is aan die deelnemers. Dit is verwag, in die aanvangs fase van sulke interaksies, dat daar baie ruimte vir die konstruksie van identiteit is. 'n Raamwerk word dan ontwikkel om die konstruksie van identiteit en vertroue in verband te bring, wat dan kan gebruik word as die basis vir die analise van narratiewe posisionering. Die raamwerk bestaan uit twee dimensies waarlangs identiteite kan geplaas word: sosiale verpligtinge en relasionele posisionering omvang. Daar word aangevoer dat disposisionele vertroue betrekking het tot relasionele posisionering omvang, terwyl die strukturele basis van vertroue verband hou met sosiale verpligtinge. Identiteit gebaseerde vertroue dui dus waar die konsultant pas binne die strukturele of disposisionele basisse van die trust. Daar word dan getoon hoe konteks modereer welke van die vertroue basisse oorheersend sal wees, en hoe hierdie kan manifesteer in die narratief van die konsultant. Dit bied drie algemene kontekste, wat elk lei tot die opkoms van 'n bepaalde dominante basis vir betroubaarheid persepsies deur die kliënte. Die besondere geval geanaliseer in die tesis korreleer met 'n spesifieke kontekste binne die raamwerk. Hierdie konteks is waar die konsultant onbekend is aan die kliënte. Die laaste deel van die tesis illustreer die gebruik van die raamwerk en konteks waar dit die ontleding van 'n spesifieke konsultant se persoonlike narratief tydens 'n aanvanklike interaksie met kliënte lei. Die analise word dan vir die konsultant se sagteware produk narratief herhaal. Die strukture van die twee verhale word dan vergelyk om te wys hoe die konsultant ook probeer het om die identiteit-gebaseerde vertroue uit te brei na sy sagteware produk.

This study examines the relationships between celebrities and their followers through social networking sites (SNS). A total of 239 participants completed the survey through MTurk. The results show that celebrities’ self-disclosure on SNS increases their Parasocial Interaction (PI) with fans. In addition, when a celebrity is perceived as trustworthy, s/he would have a higher PI with fans. Meanwhile, celebrities’ self-disclosure was not associated with trustworthiness. Furthermore, time spent on SNS was also not associated with PI. This study also found that type of celebrity does not determine the degree of influence they have on the followers. People have almost same parasocial interaction with their favorite celebrity whether the celebrity is a singer, athlete, actor, or any other. Additionally, there is no specific social networking site on which people have a stronger PI with celebrities. PI with celebrities on Facebook, YouTube, Twitter, Instagram, and the other platforms is almost the same.

Il lavoro, composto da tre articoli, si focalizza sulla relazione tra leadership e performance, indagata e osservata da molteplici punti di vista e attraverso differenti strategie di ricerca, ma sempre in un contesto pubblico o comunque mission-driven. In particolare, il primo articolo indaga la relazione tra leadership e performance organizzativa, con un duplice obiettivo: da un lato validare da un punto di vista metodologico la scala di misurazione più utilizzata, dall’altro verificarne la relazione con la performance organizzativa utilizzando una scala più parsimoniosa. Gli altri due articoli si focalizzano sulla relazione tra leadership e performance individuale: il primo esplora, attraverso un disegno di ricerca qualitativo, il ruolo del feedback fornito dal superiore nel processo di riflessione critica dei collaboratori, volto al cambiamento dei comportamenti e al miglioramento della propria performance; il secondo indaga, attraverso un disegno di ricerca sperimentale, gli effetti della credibilità dei leader sulla performance dei collaboratori, anche mediante la percezione da parte dei dipendenti dell’importanza e dell’utilità del proprio lavoro per gli altri. / The three papers included in the thesis focus on the relationship between leadership and performance, investigated and observed from multiple points of view and through different research strategies. All the papers are conducted in a public or mission-driven setting. The first article focuses on the relationship between leadership and organizational performance, with a twofold objective: on the one hand, to validate the most used measurement scale for leadership from a methodological point of view, and, on the other, to verify the relationship with organizational performance using a more parsimonious scale. The other two articles focus on the relationship between leadership and individual performance. One explores, through a qualitative research design, the role of feedback provided by the supervisor in employees’ critical reflection process, aimed at changing their behaviors and at improving their own performance. The last one investigates, through an experimental research design, the effects of leaders’ trustworthiness on the performance of employees, through the employees' perception of the task significance of their job.

Past studies, that studied facial attractiveness, focus mainly on fluctuating asymmetry, averageness, masculinity, femininity, and skin coloration influences on attractiveness assessment. Their findings have been used by intercultural studies. They have revealed that people from diverse areas prefer differential development of sexually dimorphic cues, according to, e.g. local health and economic situation. We have done an online questionnaire survey. We included Czech (N = 100), Iranian (N = 87) and Turkish (N = 185) facial stimuli and raters of both sexes. We have studied whether members of all the populations would utilize the facial colouration and sexual dimorphism cues in a similar way. We have also tested whether there were differences in the facial width to height ratio (fWHR) between the sexes in all the populations. We have also wondered if the populations differed in the variance of facial skin colouration. Raters from all the populations saw feminine women as attractive. Turks and Czechs found masculine men as attractive, while Iranian women found more average Iranian men as attractive. Averageness positively predicted the attractiveness of the Czech and Turkish faces of both sexes. Older and more average Czech men were considered more masculine by Czech women. More average and younger Czech...