42 resultados para Statistics, Probability and Uncertainty

em Deakin Research Online - Australia


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Sixteen young (25±2.6 years) and 16 older individuals (69±4.4 years) walked normally then terminated walking rapidly. A visual stopping stimulus was presented 10 ms following ground contact (short delay) and in another condition, at 450 ms prior to toe-off (long delay). Stimulus probability was either high (80% of trials) or low (10%). The younger group stopped faster (463 vs. 574 ms) despite also walking faster (1.29 vs. 1.17 m s−1). Longer delay decreased one-step responses but older participants used significantly more (slower) two-step stopping, which increased stopping time and distance. The additional step may have been pre-planned to maintain medial–lateral stability.

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The usage of Ecstasy and related drug (ERD) has increasingly been the focus of epidemiological and other public health-related research. One of the more promising methods is the use of the Internet as a recruitment and survey tool.However, there remain methodological concerns and questions about representativeness. Three samples of ERD users in Melbourne, Australia surveyed in 2004 are compared in terms of a number of key demographic and drug use variables. The Internet, face-to-face, and probability
sampling methods appear to access similar but not identical groups of ERD users. Implications and limitations of the study are noted and future research is recommended.

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In this article we examine the ways discourses of risk manifested and played out within and across two groups of Australian mothers living in two large urban centres in Australia: the first comprised of mothers who had a pre-teen child diagnosed with an eating disorder (n = 13); the second of mothers who had a pre-teen child without the symptoms or diagnosis of an eating disorder (n = 13). In 2011 and 2012, we conducted in-depth interviews with the mothers in their homes on their ideas about health and their relationships with their children. An analysis of the data collected from these interviews indicated that having a pre-teen child diagnosed with an eating disorder had a decisive impact on how the mothers constituted and responded to risk. For mothers, who had a pre-teen child with an eating disorder, risk was intensified by bio-medical discourses. The particular intensifications of risk limited the ways in which mothers could act and often threatened to undermine their abilities as competent carers. By contrast, the mothers who did not have a pre-teen child with an eating disorder spoke about risk less directly, and with less sense of immediacy. Where these mothers acknowledged risk discourses particularly in regard to health, they were in a stronger position to negotiate them. Our analysis indicates that the ways in which mothers responded to risk is contingent on circumstances and contexts. Mothers’ responses to risk were related to the calculability of the risk and their perceived capacity to manage it.

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In an influential paper Pesaran ('A simple panel unit root test in presence of cross-section dependence', Journal of Applied Econometrics, Vol. 22, pp. 265-312, 2007) proposes two unit root tests for panels with a common factor structure. These are the CADF and CIPS test statistics, which are amongst the most popular test statistics in the literature. One feature of these statistics is that their limiting distributions are highly non-standard, making for relatively complicated implementation. In this paper, we take this feature as our starting point to develop modified CADF and CIPS test statistics that support standard chi-squared and normal inference.

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The thesis highlights how women reconstruct themselves after mammography, following a positive diagnosis of cancer, and post mastectomy. It juxtaposes women's experiences of breast cancer with doctors' perceptions of their role in treating patients, allowing an understanding of how risk and uncertainty are transferred between the private and public spheres.

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In this article three unit root tests that allow for a break in both the seasonal mean and linear trend of the data are proposed. The tests, which can be seen as small-sample corrected versions of already known asymptotic tests, are shown to perform very well in simulations, and much better than their asymptotic counterparts.

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Technologies, such as Atomic Force Microscopy (AFM), have proven to be one of the most versatile research equipments in the field of nanotechnology by providing physical access to the materials at nanoscale. Working principles of AFM involve physical interaction with the sample at nanometre scale to estimate the topography of the sample surface. Size of the cantilever tip, within the range of few nanometres diameter, and inherent elasticity of the cantilever allow it to bend in response to the changes in the sample surface leading to accurate estimation of the sample topography. Despite the capabilities of the AFM, there is a lack of intuitive user interfaces that could allow interaction with the materials at nanoscale, analogous to the way we are accustomed to at macro level. To bridge this gap of intuitive interface design and development, a haptics interface is designed in conjunction with Bruker Nanos AFM. Interaction with the materials at nanoscale is characterised by estimating the forces experienced by the cantilever tip employing geometric deformation principles. Estimated forces are reflected to the user, in a controlled manner, through haptics interface. Established mathematical framework for force estimation can be adopted for AFM operations in air as well as in liquid mediums.

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Objective: To estimate the prevalence of constipation and laxative use in a sample of people 65 years and over and examine relationships between usual diet and constipation.
Design: A mailed survey using validated instruments to measure bowel habit and laxative use with follow-up interviews to collect dietary data.
Subjects and setting: Three hundred and thirty people aged 65 years and over living at home in Melbourne were randomly selected from the electoral roll of a federal electorate.
Statistical analysis: Descriptive statistics, frequencies and two sample t-tests were used.
Results: Seventy-nine people responded to the mailed bowel survey and 61 were interviewed to collect food intake data. The proportion of constipated people was approximately one quarter (n = 18). Laxative use in the previous 12 months was reported by a fifth of respondents and in these subjects one in four was not constipated. Analysis of the dietary data revealed that the average number of cereal and vegetable serves consumed per day was similar to the national average but less than recommended by nutrition bodies although fruit intake met these recommendations. Constipated subjects consumed fewer serves from the cereals food group than those who were not constipated (2.9 and 3.5 serves respectively, P = 0.03).
Conclusion: Constipation and laxative use appears to be as common in older Australians as in similar populations overseas. Low intake of cereal foods may be a contributing factor.

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Focuses on a national project that analyzed Australian research on primary school numeracy from 1994 to 2004. Effective teaching methods used in numeracy education; Summary of children's development of specific mathematical concepts; Findings of several researches on primary school probability and statistics, measurement, number, space and equity.

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Purpose – The aim of this paper is to provide a critical evaluation of the potential of new institutional economics (NIE) in third world development.

Design/methodology/approach – The paper reviews various theories under NIE from both conceptual and empirical perspectives. It then reviews the various definitions of institutions and show that institutions are essential to overcome problems of information and uncertainty.

Findings – The review finds that weak institutions can undermine development and hence governments in developing countries should strengthen their institutions to provide greater scope for efficient functioning of markets. Where the market does not work owing to high transactions costs, traditional institutions of collective action and group decision making can work and hence need to be recognised.

Research limitations/implications – The major implications of the paper is that in developing countries, a clear understanding of various institutions such as user groups, inter-linked credit markets, rotational irrigation etc. is needed before they are replaced or modified by other institutions. The main limitations of NIE are that there can be capture by elites of various institutional innovations in rural areas, and that it does not explicitly consider income distribution and uncertainty which are glossed over and hence remain areas for future research.

Originality/value – This paper critically reviews the various institutional environments that developing countries face in addressing development issues.

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The paper responds to the release of both the AusCERT and CSI/FBI computer crime and security surveys with a comparison of the results between the two countries' respondents. Overall both surveys show the trend that most organisations employ security technologies but half of them still experience incidents which compromise their security. These incidents have significant quantifiable losses but despite these organisations are still loathed to report to law enforcement agencies for various reasons. These include the impression that law enforcement agencies are not interested, and the negative publicity such incidents can cause in their aftermath.

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Faced with increasing environmental complexity and uncertainty, organisations have been urged to replace traditional bureaucratic structures with more flexible, responsive forms of organising. However, the emerging paradox is that exploration and experimentation, features of new forms of organising, benefit from the planning, coordinating and direction-setting mechanisms that underpin traditional forms of organising. It is therefore important to recognise the distinctive and complementary features of traditional and new forms of organising. This demands a dualities-sensitive perspective which encourages, rather than tries to resolve, a constructive tension between seemingly contradictory organising forms such as flexibility and efficiency, autonomy and control, hierarchy and networks, focus and diversification. Managing continuity and change through forms of organising becomes central to building healthy organisations.

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This paper examines the role of organizing forms in strategizing for change. It argues that a duality approach aids in understanding how organizing influences and leverages strategizing for change. Three propositions are presented.

First, organizing is strategizing. This represents the interaction between organizing and strategizing, where organizing forms enable and constrain strategic change. Second, tension in forms of organizing can be the source of strategic advantage. The main challenge is to develop systems that function best in tension, delivering both efficiency and innovation. A dualities approach emphasizes the need not only to hold fast to routines but also to attempt to subvert them with innovations. It is this combination that facilitates strategic change. Third, heterogeneity in organizing forms offers strategic adaptability by providing increased opportunities for innovation.

This paper concludes that despite the appeal of calls for organizations to become capable of constant change, the advantages of flexibility are compromised by the disadvantages of instability and uncertainty. Furthermore, the study of organizing forms reveals that change is continuous at the micro level but discontinuous at the macro level. Thus the relationship between organizing and strategizing can subsequently be non-linear and recursive, with strategic advantages achieved through tension and heterogeneity in organizing.

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Security protocols have been recently found with subtle flaws due to incomplete or ambiguous specification. Although formal methods have remarkably assisted in protocol analysis, they ignores the effect of hostile/uncertain environment, which might lead to inconsistent belief that can be held by principals in delivered messages. This discrepant belief may prevent us from representing the insecurity and uncertainty in a real trading situation. Unfortunately, the current approaches lack the ability to handle the inconsistent belief. This article presents a probabilistic method, which intuitively measures the belief from different principals that can be put on the goal of the protocol. The experiments demonstrate our method is useful to enhance the protocol analysis.

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Background: The burden of breast cancer expressed in Disability Adjusted Life Years (DALYs) was compared for six European countries and its sensitivity to different sources of variation examined. Methods: DALYs were calculated using country-specific epidemiological data and European Disability Weights. Epidemiological data for 1996 were obtained for Denmark, England and Wales, France, the Netherlands, Spain and Sweden. Disability weights were empirically derived. Results:  Denmark and the Netherlands lost the largest number of DALYs (approximately 1100 DALYs per 100,000 women). They were followed by England (87% of the Danish burden), France (72%), Sweden (68%) and Spain (67%). 70 to 80% of the burden was caused by mortality. Cross-national variation in disease epidemiology was the largest source of variation in the burden of breast cancer. Variation in disability weights and uncertainty in epidemiological data had smaller effects. Conclusion: To compare the burden of breast cancer and most other types of cancer mortality rates provide sufficient information.