138,237 research outputs found

    A Convex Optimization Approach to the Design of Multiobjective Discrete Time Systems

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    One of the most important contributions of robust control theory has been the devel opment of a new framework for the design and analysis of feedback systems satisfying mixed time-frequency specifications. This framework is given by the Linear Matrix Inequality (LMI) approach where design and analysis problems are posed as convex optimization problems subject to affine matrix constraints. Most of the focus in this area has been on continuous-time systems design with very few results for discretetime systems. One of the main contributions of this work is the development and implementation of a MATLAB toolbox for discrete-time controller design using the LMI approach. Another important contribution is the development of a new linear matrix inequality for peak-to-peak gain minimization that allows the use of projec tion formulas for l1-design. In order to illustrate the advantages and effectiveness of the LMI framework to multiobjective design problems it was applied to design a noise-shaping feedback coder. This nonlinear circuit is an important component of (Sigma) - (Delta) modulators. This work shows that a robust control approach based on LMIs provides a rigorous framework for the systematic analysis and design of these coders in contrast to existing ad hoc methods used traditionally for such designs

    Purity or pragmatism? : Reflecting on the use of systematic review methodology in development

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    Systematic review methodology pioneered in health care has been increasingly applied to development questions of importance in lower- and middle-income countries. This paper reports one such review on the topic of microfinance in sub-Saharan Africa and reflects on the number of pragmatic methodological compromises made when applying the method to a new field. These compromises relate to multidisciplinary teamwork, application of regional filters, drawing on evidence from additional study types and exploring mechanisms for change through the development and testing of a causal pathway. The paper concludes that a pragmatic rigorous approach to systematically reviewing evidence of effectiveness is needed for international development

    Using mixed methods in monitoring and evaluation : experiences from international development

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    This paper provides an overview of the various ways in which mixing qualitative and quantitative methods could add value to monitoring and evaluating development projects. In particular it examines how qualitative methods could address some of the limitations of randomized trials and other quantitative impact evaluation methods; it also explores the importance of examining"process"in addition to"impact", distinguishing design from implementation failures, and the value of mixed methods in the real-time monitoring of projects. It concludes by suggesting topics for future research -- including the use of mixed methods in constructing counterfactuals, and in conducting reasonable evaluations within severe time and budget constraints.Poverty Monitoring&Analysis,Scientific Research&Science Parks,Science Education,Poverty Impact Evaluation,Statistical&Mathematical Sciences

    Investigating information systems with mixed-methods research

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    Mixed-methods research, which comprises both quantitative and qualitative components, is widely perceived as a means to resolve the inherent limitations of traditional single method designs and is thus expected to yield richer and more holistic findings. Despite such distinctive benefits and continuous advocacy from Information Systems (IS) researchers, the use of mixed-methods approach in the IS field has not been high. This paper discusses some of the key reasons that led to this low application rate of mixed-methods design in the IS field, ranging from misunderstanding the term with multiple-methods research to practical difficulties for design and implementation. Two previous IS studies are used as examples to illustrate the discussion. The paper concludes by recommending that in order to apply mixed-methods design successfully, IS researchers need to plan and consider thoroughly how the quantitative and qualitative components (i.e. from data collection to data analysis to reporting of findings) can be genuinely integrated together and supplement one another, in relation to the predefined research questions and the specific research contexts

    Measuring the Impact of Youth Voluntary Service Programs

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    Summary and Conclusions of a meeting of international experts hosted by the World Bank and Innovations in Civic Participation to discuss evaluation of the impact of youth civic engagement on development

    Research Design, as Independent of Methods

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    Objectives •Readers of this chapter should be in a better position to: •Understand the process of research design •Place their own and others work within a full cycle or programme of ongoing research •Understand why good research almost always involves a mixture of evidence •Defend themselves from those who want numbers and text to be enemies rather than allies •Argue that good research is more ethical for society than poor researc

    Civic Engagement Programs and Youth Development: A Synthesis

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    Focuses on the role that civic engagement plays in helping young people develop a broad array of strengths and capacities, including educational achievement, health and safety, social and emotional well-being, and self sufficiency

    Challenges in impact evaluation of development interventions: opportunities and limitations for randomized experiments

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    In recent years debates on as well as funding of impact evaluations of development interventions have flourished. Unfortunately, controversy regarding the promotion and application of randomized experiments (RE) has led to a sense of polarization in the development policy and evaluation community. As some proponents claim epistemological supremacy of REs (with respect to attribution) the counter reaction among others has been rejection. Needless to say, such extreme positions are counterproductive to reaching a goal that is commonly endorsed: to learn more about what works and why in development. This paper discusses the prospects and limitations of REs from the perspective of three categories of challenges in impact evaluation: delimitation and scope, attribution versus explanation, and implementation challenges. The implicit lesson is twofold. First of all, the question ‘to randomize or not to randomize’ is overrated in the current debate. Limitations in scope, applicability as well as implementation will necessarily restrict the use of REs in development impact evaluation. There is a risk that the current popularity of REs in certain research and policy circles might lead to a backlash as too high expectations of REs may quicken its demise. More importantly, given the nature and scope of the challenges discussed in the paper, more energy should be devoted to developing and testing ‘rigorous’ mixed method approaches within a framework of theory-driven evaluation.
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