778 resultados para worst-case analysis
Resumo:
In this poster we presented our preliminary work on the study of spammer detection and analysis with 50 active honeypot profiles implemented on Weibo.com and QQ.com microblogging networks. We picked out spammers from legitimate users by manually checking every captured user's microblogs content. We built a spammer dataset for each social network community using these spammer accounts and a legitimate user dataset as well. We analyzed several features of the two user classes and made a comparison on these features, which were found to be useful to distinguish spammers from legitimate users. The followings are several initial observations from our analysis on the features of spammers captured on Weibo.com and QQ.com. ¦The following/follower ratio of spammers is usually higher than legitimate users. They tend to follow a large amount of users in order to gain popularity but always have relatively few followers. ¦There exists a big gap between the average numbers of microblogs posted per day from these two classes. On Weibo.com, spammers post quite a lot microblogs every day, which is much more than legitimate users do; while on QQ.com spammers post far less microblogs than legitimate users. This is mainly due to the different strategies taken by spammers on these two platforms. ¦More spammers choose a cautious spam posting pattern. They mix spam microblogs with ordinary ones so that they can avoid the anti-spam mechanisms taken by the service providers. ¦Aggressive spammers are more likely to be detected so they tend to have a shorter life while cautious spammers can live much longer and have a deeper influence on the network. The latter kind of spammers may become the trend of social network spammer. © 2012 IEEE.
Resumo:
This study proposes an integrated analytical framework for effective management of project risks using combined multiple criteria decision-making technique and decision tree analysis. First, a conceptual risk management model was developed through thorough literature review. The model was then applied through action research on a petroleum oil refinery construction project in the Central part of India in order to demonstrate its effectiveness. Oil refinery construction projects are risky because of technical complexity, resource unavailability, involvement of many stakeholders and strict environmental requirements. Although project risk management has been researched extensively, practical and easily adoptable framework is missing. In the proposed framework, risks are identified using cause and effect diagram, analysed using the analytic hierarchy process and responses are developed using the risk map. Additionally, decision tree analysis allows modelling various options for risk response development and optimises selection of risk mitigating strategy. The proposed risk management framework could be easily adopted and applied in any project and integrated with other project management knowledge areas.
Resumo:
Although considerable effort has been invested in the measurement of banking efficiency using Data Envelopment Analysis, hardly any empirical research has focused on comparison of banks in Gulf States Countries This paper employs data on Gulf States banking sector for the period 2000-2002 to develop efficiency scores and rankings for both Islamic and conventional banks. We then investigate the productivity change using Malmquist Index and decompose the productivity into technical change and efficiency change. Further, hypothesis testing and statistical precision in the context of nonparametric efficiency and productivity measurement have been used. Specially, cross-country analysis of efficiency and comparisons of efficiencies between Islamic banks and conventional banks have been investigated using Mann-Whitney test.
Resumo:
Ignorance of user factors can be seen as one of the nontechnical issues contributing to expert system failure. An expert advisory system is built for nonexpert users; the users' acceptance is a very important factor for its successful implementation. If an expert advisory system satisfactorily represents the expertise in the domain, there still remains the question: "Will the end-users use the system?" This paper aims to address users' issues by analysing their reactions towards an expert advisory system called ADGAME, developed to help its users make better decisions in playing a competitive business game. Two experiments with ADGAME have been carried out. The research results show that, when the use of the expert advisory system is optional, there is considerable reluctance to use it, particularly amongst the "worst" potential users. Users also doubt the potential benefits in terms of improved learning and confidence in decisions made. Strangely, the one positive expectation that users had, that the system would save them time, proved not to be the case in practice; ADGAME appears to improve the users' effectiveness rather than their efficiency. © 1995.
Resumo:
We analyse the performance persistence of Islamic and Socially Responsible Investment (SRI) mutual funds. We adopt a multi-stage strategy in which, in the first stage, partial frontiers’ approaches are considered to measure the performance of the different funds in the sample. In the second stage, the results yielded by the partial frontiers are plugged into different investment strategies based on a recursive estimation methodology whose persistence performance is evaluated in the third stage of the analysis. Results indicate that, for both types of funds, performance persistence actually exists, but only for the worst and, most notably, best funds. This result is robust not only across methods (and different choices of tuning parameters within each method) but also across both SRI and Islamic funds—although in the case of the latter persistence was stronger for the best funds. The persistence of SRI and Islamic funds represents an important result for investors and the market, since it provides information on both which funds to invest in and which funds to avoid. Last but not least, the use of the aforementioned techniques in the context of mutual funds could also be of interest for the non-conclusive literature.
Resumo:
Projects that are exposed to uncertain environments can be effectively controlled with the application of risk analysis during the planning stage. The Analytic Hierarchy Process, a multiattribute decision-making technique, can be used to analyse and assess project risks which are objective or subjective in nature. Among other advantages, the process logically integrates the various elements in the planning process. The results from risk analysis and activity analysis are then used to develop a logical contingency allowance for the project through the application of probability theory. The contingency allowance is created in two parts: (a) a technical contingency, and (b) a management contingency. This provides a basis for decision making in a changing project environment. Effective control of the project is made possible by the limitation of the changes within the monetary contingency allowance for the work package concerned, and the utilization of the contingency through proper appropriation. The whole methodology is applied to a pipeline-laying project in India, and its effectiveness in project control is demonstrated.
Resumo:
The impact of ICT (information and communications technology) on the logistics service industry is reshaping its organisation and structure. Within this process, the nature of changes resulting from ICT dissemination in small 3PLs (third party logistics providers) is still unclear, although a large number of logistics service markets, especially in the EU context, are populated by a high number of small 3PLs. In addition, there is still a gap in the literature where the role of technological capability in small 3PLs is seriously underestimated. This gives rise to the need to develop investigation in this area. The paper presents the preliminary results of a case study analysis on ICT usage in a sample of 7 small Italian 3PLs. The results highlight some of the barriers to effective ICT implementation, as well as some of the critical success factors.
Resumo:
ICT has triggered many changes in the logistics service industry. New technology is reshaping the organisation and structure of this industry as ICT impacts significantly on the operations of 3PLs. Within this process, while large 3PLs are gaining substantial benefits from technology usage, the nature of changes resulting from ICT usage in small 3PLs remains unclear. This is critical particularly for those markets populated by a high number of small 3PLs such as the Italian logistics industry. From the research point of view, there is still a gap in the literature where the role of technological capability in small 3PLs are seriously underestimated. This gives rise to the need to develop investigation in this area. This paper presents the preliminary results of a case study analysis on ICT usage in a sample of 7 small Italian 3PLs. The results highlight some of the barriers to effective ICT implementation, as well as some of the critical success factors.
Resumo:
Abstract (provisional): Background Failing a high-stakes assessment at medical school is a major event for those who go through the experience. Students who fail at medical school may be more likely to struggle in professional practice, therefore helping individuals overcome problems and respond appropriately is important. There is little understanding about what factors influence how individuals experience failure or make sense of the failing experience in remediation. The aim of this study was to investigate the complexity surrounding the failure experience from the student’s perspective using interpretative phenomenological analysis (IPA). Methods The accounts of 3 medical students who had failed final re-sit exams, were subjected to in-depth analysis using IPA methodology. IPA was used to analyse each transcript case-by-case allowing the researcher to make sense of the participant’s subjective world. The analysis process allowed the complexity surrounding the failure to be highlighted, alongside a narrative describing how students made sense of the experience. Results The circumstances surrounding students as they approached assessment and experienced failure at finals were a complex interaction between academic problems, personal problems (specifically finance and relationships), strained relationships with friends, family or faculty, and various mental health problems. Each student experienced multi-dimensional issues, each with their own individual combination of problems, but experienced remediation as a one-dimensional intervention with focus only on improving performance in written exams. What these students needed to be included was help with clinical skills, plus social and emotional support. Fear of termination of the their course was a barrier to open communication with staff. Conclusions These students’ experience of failure was complex. The experience of remediation is influenced by the way in which students make sense of failing. Generic remediation programmes may fail to meet the needs of students for whom personal, social and mental health issues are a part of the picture.
Resumo:
Purpose – This paper aims to clarify what ‘narrative analysis’ may entail when it is assumed that interview accounts can be treated as (collections of) narratives. What is considered a narrative and how these may be analyzed is open to debate. After suggesting an approach of how to deal with narrative analysis, the authors critically discuss how far it might offer insights into a particular accounting case. Design/methodology/approach – After having explained what the authors’ view on narrative analysis is, and how this is linked with the extant literature, the authors examine the socialisation processes of two early career accountants that have been articulated in an interview context. Findings – The approach to narrative analysis set out in this paper could help to clarify how and why certain interpretations from an interview are generated by a researcher. The authors emphasise the importance of discussing a researcher’s process of discovery when an interpretive approach to research is adopted. Research limitations/implications – The application of any method, and what a researcher thinks can be distilled from this, depends on the research outlook he/she has. As the authors adopt an interpretive approach to research in this paper, they acknowledge that the interpretations of narratives, and what they deem to be narratives, will be infused by their own perceptions. Practical implications – The authors believe that the writing-up of qualitative research from an interpretive stance would benefit from an explicit acceptance of the equivocal nature of interpretation. The way in which they present and discuss the narrative analyses in this paper intends to bring this to the fore. Originality/value – Whenever someone says he/she engages in narrative analysis, both the “narrative” and “analysis” part of “narrative analysis” need to be explicated. The authors believe that this only happens every so often. This paper puts forward an approach of how more clarity on this might be achieved by combining two frameworks in the extant literature, so that the transparency of the research is enhanced.
Resumo:
2000 Mathematics Subject Classification: 62H30, 62J20, 62P12, 68T99