Regularized Linear Discriminant Analysis Using a Nonlinear Covariance Matrix Estimator

Linear discriminant analysis (LDA) is a widely used technique for data classification. The method offers adequate performance in many classification problems, but it becomes inefficient when the data covariance matrix is ill-conditioned. This often occurs when the feature space's dimensionality is higher than or comparable to the training data size. Regularized LDA (RLDA) methods based on regularized linear estimators of the data covariance matrix have been proposed to cope with such a situation. The performance of RLDA methods is well studied, with optimal regularization schemes already proposed. In this paper, we investigate the capability of a positive semidefinite ridge-type estimator of the inverse covariance matrix that coincides with a nonlinear (NL) covariance matrix estimator. The estimator is derived by reformulating the score function of the optimal classifier utilizing linear estimation methods, which eventually results in the proposed NL-RLDA classifier. We derive asymptotic and consistent estimators of the proposed technique's misclassification rate under the assumptions of a double-asymptotic regime and multivariate Gaussian model for the classes. The consistent estimator, coupled with a one-dimensional grid search, is used to set the value of the regularization parameter required for the proposed NL-RLDA classifier. Performance evaluations based on both synthetic and real data demonstrate the effectiveness of the proposed classifier. The proposed technique outperforms state-of-art methods over multiple datasets. When compared to state-of-the-art methods across various datasets, the proposed technique exhibits superior performance.Comment: \c{opyright} 2024 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other work

Quantifying Privacy: A Novel Entropy-Based Measure of Disclosure Risk

It is well recognised that data mining and statistical analysis pose a serious treat to privacy. This is true for financial, medical, criminal and marketing research. Numerous techniques have been proposed to protect privacy, including restriction and data modification. Recently proposed privacy models such as differential privacy and k-anonymity received a lot of attention and for the latter there are now several improvements of the original scheme, each removing some security shortcomings of the previous one. However, the challenge lies in evaluating and comparing privacy provided by various techniques. In this paper we propose a novel entropy based security measure that can be applied to any generalisation, restriction or data modification technique. We use our measure to empirically evaluate and compare a few popular methods, namely query restriction, sampling and noise addition.Comment: 20 pages, 4 figure

Saudi international students’ perceptions of their transition to the UK and the impact of social media

In their transition to a new country, international students often feel lost, anxious or stressed. Saudi students in the UK in particular may face further challenges due to the cultural, social and religious differences that they experience. There is a lot of evidence that social media play a crucial role in this experience. By interviewing 12 Saudi students from different cities in the UK, the aim of this study is to investigate how they perceive their transition to the UK and how social media is involved. The analysis indicates that Saudi students’ perceptions of transition tend to fall in to one of two markedly different camps. Some students see transition as an opportunity to detach themselves from their home country and to engage with the new society. Those students turn to social media as a tool allowing them to build bridges with the new society. Other students feel less enthusiastic to make a full engagement with the UK society. Those students find social media as a good tool to maintain connections and links with family and friends in their home country

Qualifications and ethics education: The views of ICT professionals

Do information and communications technology (ICT) professionals who have ICT qualifications believe that the ethics education they received as part of their ICT degrees helped them recognise ethical problems in the workplace and address them? If they do, are they also influenced by their personal ethics? What else helps them recognise ethical problems in the workplace and address them? And what are their views in relation to the impact of ethics education on professionalism in the ICT workplace? A quantitative survey of 2,315 Australian ICT professionals revealed that participants who reported having various levels of qualifications found ethics education or training, to a small degree, helpful for recognising ethical problems and addressing them; although it is those with Non-ICT qualifications, not those with ICT degrees, who were influenced more by ethics education or training. This suggests that educators need to consider how to better prepare ICT graduates for the workplace challenges and the types of situations they subsequently experience. The survey also found that participants who reported having various levels of qualifications were not influenced by their personal ethics or indeed any other factor making ethics education or training important for developing professionalism. The quantitative survey was followed by qualitative interviews with 43 Australian ICT professionals in six Australian capital cities. These interviews provided further empirical evidence that ethics education is crucial for enabling ICT professionals to recognise ethical problems and resolve them and that educators need to consider how to better prepare ICT graduates for the types of moral dilemmas that they are likely going to face in the workforce

Internet resources to help Australian ICT professionals identify and solve ethical challenges

ICT professionals need a way to understand the ethical challenges they face in the workplace. Having first identified common workplace challenges through an industry survey with 2,315 respondents, those challenges were further explored, as were solutions to them, through interviews with 43 participants in six Australian capital cities. Findings from the quantitative survey were consistent with the findings from the qualitative interviews. That led to the identification of common categories of ethical challenges and strategies for solving them. Common unethical behaviours in the ICT workplace were also identified. The findings to date suggest that internal strategies are more effective in dealing with ethical workplace issues compared to external strategies. Further research is underway to clarify how those strategies can best be presented in an Internet resource, and the proactive steps that can be taken to create work environments that mitigate against unethical behaviours

Elastic metaphors : expanding the philosophy of interface design

Metaphors are generally accepted as essential to the design of effective human computer interfaces. However, "The generally assumed theoretical benefits of user interface metaphor are supported by surprisingly little empirical evidence." (Blackwell, 1998). This paper discusses the concept of "concrete metaphor" and the problems that it presents in interface and interaction design. Concrete metaphors are composed of objects that users are familiar with from their everyday experience (L'Abbate and Hemmje, 1998). Since we live in a physical world, then it seems natural that computer interfaces should resemble as closely as possible -- physical objects. We already know how these devices work, and so a metaphor based on the known should help us to understand the unknown. After all, "The essence of metaphor is understanding and experiencing one kind of thing in terms of another." (Lakoff and Johnson, 1980) Certainly, this has been the prevailing school of thought when discussing the application of metaphor to Human Computer Interface (HCI) design.However, there is another school of thought that the use of metaphor is detrimental to HCI design. For example, Halasz and Moran (1982, p. 386) considered analogy as "dangerous when used for detailed reasoning about computer systems - this is much better done with abstract conceptual models."Our argument is that metaphor can be used for the representation and explanation of abstract conceptual models. Recent work by Lakoff and Núñez (2001) describes the notion of conceptual metaphor -- a cognitive mechanism that derives abstract thinking from the way we function in the everyday physical world.The new approach towards the application of metaphor to human computer interactions, proposed in this paper, is based on the concept of 'elastic metaphors'. The paper presents the features of elastic metaphors and methods for its construction