This thesis presents a modification of existing entropy-based splitting criteria for classification and regression trees. Trees are typically grown using splitting criteria that choose optimal splits without taking future splits into account. This thesis examines localised splitting criteria that are based on local averaging in regression trees or local proportions in classification trees. The use of a localised criterion is motivated by the fact that future splits result in leaves that contain local observations, and hence local deviances provide a better approximation of the deviance of the fully grown tree. While most recent research has focussed on tree-averaging techniques that are aimed at taking a moderately successful splitting criterion and improving its predictive power, this thesis concentrates on improving the splitting criterion. Use of a localised splitting criterion captures local structures and enables later splits to capitalise on the placement of earlier splits when growing a tree. Using the localised splitting criterion results in much simpler trees for pure interaction data (data with no main effects) and can produce trees with fewer errors and lower residual mean deviances than those produced using a global splitting criterion when applied to real data sets with strong interaction effects. The superiority of the localised splitting criterion can persist when multiple trees are grown and averaged using simple methods. Although a single tree grown using the localised splitting criterion can outperform tree averaging using the global criterion, generally improvements in predictive performance are achieved by utilising the localised splitting criterion's property of detecting local discontinuities and averaging over sets of trees grown by placing splits where the deviance is locally minimal. Predictive performance improves further when the degree of localisation of the splitting criterion is randomly selected and weighted randomisation is used with locally minimal deviances to produce sets of trees to average over. Although state of the art methods quickly average very large numbers of trees, thus making the performance of the splitting criterion less critical, predictive performance when the localised criterion is used in bagging indicates that different splitting methods warrant investigation. The localised splitting criterion is most useful for growing one tree or a small number of trees to examine structure in the data. Structurally different trees can be obtained by simply splitting the data where the localised splitting criterion is locally optimal.

Thesis (M.S.)--University of Michigan, 1987.

Thesis (M.S.)--University of Michigan, 1987.

This thesis considers the tasks involved in exploratory analysis of temporal graph data, and the visual techniques which are able to support these tasks. There has been an enormous increase in the amount and availability of graph (network) data, and in particular, graph data that is changing over time. Understanding the mechanisms involved in temporal change in a graph is of interest to a wide range of disciplines. While the application domain may differ, many of the underlying questions regarding the properties of the graph and mechanism of change are the same. The research area of temporal graph visualisation seeks to address the challenges involved in visually representing change in a graph over time. While most graph visualisation tools focus on static networks, recent research has been directed toward the development of temporal visualisation systems. By representing data using computer-generated graphical forms, Information Visualisation techniques harness human perceptual capabilities to recognise patterns, spot anomalies and outliers, and find relationships within the data. Interacting with these graphical representations allow individuals to explore large datasets and gain further insightinto the relationships between different aspects of the data. Visual approaches are particularly relevant for Exploratory Data Analysis (EDA), where the person performing the analysis may be unfamiliar with the data set, and their goal is to make new discoveries and gain insight through its exploration. However, designing visual systems for EDA can be difficult, as the tasks which a person may wish to carry out during their analysis are not always known at outset. Identifying and understanding the tasks involved in such a process has given rise to a number of task taxonomies which seek to elucidate the tasks and structure them in a useful way. While task taxonomies for static graph analysis exist, no suitable temporal graph taxonomy has yet been developed. The first part of this thesis focusses on the development of such a taxonomy. Through the extension and instantiation of an existing formal task framework for general EDA, a task taxonomy and a task design space are developed specifically for exploration of temporal graph data. The resultant task framework is evaluated with respect to extant classifications and is shown to address a number of deficiencies in task coverage in existing works. Its usefulness in both the design and evaluation processes is also demonstrated. Much research currently surrounds the development of systems and techniques for visual exploration of temporal graphs, but little is known about how the different types of techniques relate to one another and which tasks they are able to support. The second part of this thesis focusses on the possibilities in this area: a design spaceof the possible visual encodings for temporal graph data is developed, and extant techniques are classified into this space, revealing potential combinations of encodings which have not yet been employed. These may prove interesting opportunities for further research and the development of novel techniques. The third part of this work addresses the need to understand the types of analysis the different visual techniques support, and indeed whether new techniques are required. The techniques which are able to support the different task dimensions are considered. This task-technique mapping reveals that visual exploration of temporalgraph data requires techniques not only from temporal graph visualisation, but also from static graph visualisation and comparison, and temporal visualisation. A number of tasks which are unsupported or less-well supported, which could prove interesting opportunities for future research, are identified. The taxonomies, design spaces, and mappings in this work bring order to the range of potential tasks of interest when exploring temporal graph data and the assortmentof techniques developed to visualise this type of data, and are designed to be of use in both the design and evaluation of temporal graph visualisation systems.

This study investigates whether balanced forms of organizational cultures moderate the effects of potential and realized absorptive capacities (ACs) to simultaneously generate exploratory and exploitative innovations. Using empirical survey data collected from 138 small to medium-sized enterprises (SMEs), we applied partial least squares (PLS) structural equation modeling (SEM) combined with mediation and moderation analyses to test our hypotheses. Our results show that the effects of potential AC on organizations' exploratory and exploitative innovations are fully mediated by the organizations' realized AC. The positive effects of realized AC on innovation are contingent on the overall cultural balance of the organization, which, however, does not affect the strong link between potential AC and realized AC. We thus provide novel empirical insights into the multi-dimensional nature of AC and the importance of cultural equilibrium for both exploratory and exploitative innovation, which is of particular importance for ambidextrous SMEs facing dynamic markets.

The main goal of the thesis is to emphasize the importance of environmental protection in an appropriate way. In the theoretical part, geographical, historical, and cultural interests of the region are presented. It also describes the region in the aspect of orography, geology, mineralogy, and hydrology. A part of the thesis is devoted to a specific destination around the karstic system. It describes not only this geological phenomenon, but also the wild life in its vicinity. Exploration of the locality is realized by a scientific walk. It leads through ten standpoints, each of which serves for presentation and explanation of a particular phenomenon, natural rarity, or historical event. For each standpoint, an answer sheet with questions related to it is repared. The walk is intended for students of the fourth and the fifth grade of the elementary school.

This study is the first of its kind to explore the phenomenon of serial rape from a behavioural profiling perspective within the South African context. The dearth of scientific research on serial rape in South Africa has impacted negatively on the recognition and investigation of such cases. The data set for the study consisted of police dockets, victim statements, court transcripts, detectives’ reports, and correctional services reports on nine serial rapists who assaulted and/or raped a total of seventy five victims. A behavioural profiling framework that was developed from existing literature was used to systematically analyse the victim and offender data using both qualitative and quantitative data analysis techniques. Initial victim and offender profiles were constructed using key elements such as age, population group, modus operandi, and sexual behaviour of the offenders. The initial results showed that the South African serial rapists typically exhibit the same behavioural elements reported in international literature with respect to aspects such as the methods of approach utilised, average age of the victims, ages of the offenders, offender – victim relationship, and sexual acts. However, the research also illustrated that South African serial rapists also displayed some behavioural aspects that have not been reported in international literature. In particular, South African serial rapists approach and attack their victims at two different locations. The research also showed that South African serial rapists are more willing to target victims outside their own populations groups. Young children also appear to be targeted more frequently by the South African serial rapists. The South African offenders also employed a new method of approaching the intended victim (i.e. the delayed-con approach). The results are discussed in terms of the extent to which the behavioural patterns, similarities and differences with observations made in international literature, and current police practices with respect to the investigation of serial rape in South Africa could be utilised to enhance investigative processes. Also, specific areas in need of further examination are identified, as are strategies that could assist in decreasing the occurrence of ‘linkage blindness’ in serial rape investigations in South Africa. / Thesis (DPhil)--University of Pretoria, 2009. / Psychology / unrestricted

Large data sets are difficult to analyze. Visualization has been proposed to assist exploratory data analysis (EDA) as our visual systems can process signals in parallel to quickly detect patterns. Nonetheless, designing an effective visual analytic tool remains a challenge. This challenge is partly due to our incomplete understanding of how common visualization techniques are used by human operators during analyses, either in laboratory settings or in the workplace. This thesis aims to further understand how visualizations can be used to support EDA. More specifically, we studied techniques that display multiple levels of visual information resolutions (VIRs) for analyses using a range of methods. The first study is a summary synthesis conducted to obtain a snapshot of knowledge in multiple-VIR use and to identify research questions for the thesis: (1) low-VIR use and creation; (2) spatial arrangements of VIRs. The next two studies are laboratory studies to investigate the visual memory cost of image transformations frequently used to create low-VIR displays and overview use with single-level data displayed in multiple-VIR interfaces. For a more well-rounded evaluation, we needed to study these techniques in ecologically-valid settings. We therefore selected the application domain of web session log analysis and applied our knowledge from our first three evaluations to build a tool called Session Viewer. Taking the multiple coordinated view and overview + detail approaches, Session Viewer displays multiple levels of web session log data and multiple views of session populations to facilitate data analysis from the high-level statistical to the low-level detailed session analysis approaches. Our fourth and last study for this thesis is a field evaluation conducted at Google Inc. with seven session analysts using Session Viewer to analyze their own data with their own tasks. Study observations suggested that displaying web session logs at multiple levels using the overview + detail technique helped bridge between high-level statistical and low-level detailed session analyses, and the simultaneous display of multiple session populations at all data levels using multiple views allowed quick comparisons between session populations. We also identified design and deployment considerations to meet the needs of diverse data sources and analysis styles. / Science, Faculty of / Computer Science, Department of / Graduate

This study assessed falls efficacy and confidence-related changes among participants attending the a Matters of Balance/Volunteer Lay Leader (AMOB/VLL) falls prevention program for older adults, based on their residential location. Data were examined from 431 older Texans enrolled in AMOB/VLL during a two-year period, and assessed at baseline and post-intervention. Results indicate that participants significantly increased falls efficacy, reduced activity interference due to their health, and decreased the number of days limited from usual activity. Regression models show that participants, despite entering the program with lower reported health status, reported greater rates of positive change for falls efficacy and health interference compared with their baseline pre-intervention counterparts. Overall program attendance and attendance at major sessions showed the greatest influence. Findings contribute to the understanding of cognitive restructuring and strengthening variations with falls prevention program outcomes.

The Hope Scholars Programme (HSP) is an after-school programme implemented by the South African Education and Environment Project (SAEP) in Cape Town, South Africa. After-school programmes (ASPs) are widely described as programmes that are implemented independently of the school day and are aimed at improving the learning outcomes and advancement of kindergarten and high school learners. The HSP began in 1998 with a goal to equip HSP learners with foundational literacy and numeracy skills for the future education and training (FET) phase and subsequent education. HSP activities are implemented under four broad service areas: (a) academic tutoring sessions; (b) experiential learning; (c) psychosocial support services; and (d) community engagement. The scope of this evaluation was the academic component under which the programme offers intensive tutoring in mathematics, natural science and English literacy. The objective of the evaluation was to assess the implementation fidelity of the academic component for programme quality and effectiveness improvement purposes. A conceptual framework for measuring implementation fidelity by Carroll, Patterson, Wood, Booth, Rick and Balain (2007) was used to guide this evaluation. Using the logic model for the programme, the evaluation focused on examining whether the HSP sessions were implemented with the intended process mechanisms through which the programme was designed to lead to its desired academic outcomes. Both primary and secondary data were used to conduct the evaluation. Primary data were collected through oneon-one in-depth interviews with HSP staff members and the volunteer tutor and focus group interviews with the HSP learners. Secondary data were obtained through the review of the HSP documents. An inductive content analysis was employed to analyse the data. The results indicated that the academic component of the HSP was implemented with limited fidelity and poor quality. Programme implementation challenges identified need to be resolved to enhance the quality of the HSP services and programme effectiveness. This evaluation contributes to the literature on: (a) the duration and frequency of the tutorial sessions; (b) the extent to which learners attend; and (c) dropout from the programmes and causes for dropping out in the context of after-school programmes. Among the contributing factors of learner dropout from the HSP, influences that were found unique to the South African context were mistrust between the learners and their parents (mistrust at home) and sweeping of classrooms.