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  • 1
    ISSN: 1572-9761
    Schlagwort(e): agricultural landscapes ; agri-environmental policy ; Europe ; indicators on policy effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In Europe most conservation values, from biodiversity to scenic sites, are integral parts of agricultural landscapes. When these landscapes change as a result of agricultural policies, natural values – species, habitats, landscapes – are usually affected. Until recently however, these values have not been part of agricultural policies. The impacts of such new policies are difficult to evaluate because landscapes are complex and diverse, and the effects of policy are rarely immediate or causal. This paper evaluates the potential effects of Agri-environmental Regulation EC 2078/92 on European agricultural landscapes through the use of agri-environmental indicators (AEIs) on policy effects. After discussing the general framework of the evaluation methodology through the use of AEIs, we distinguish two types of agri-environmental policy (AEP) effects: policy performances and policy outcomes. The impediments to direct measurement of policy outcomes are stated. The potential for measuring policy performances are checked in two case study areas, one in Spain and one in Denmark, characterized by extensive agricultural land-uses and by the dual process of intensification/abandonment that is threatening their natural values. Both study areas are currently targeted by agri-environmental schemes under Reg. 2078/92. The realisability or availability of suitable statistical data to construct and report each AEI is stated for both types of effects. A problem of scale and content is found in most of the available statistics for assessing policy outcomes and the need for data at farm level is concluded to be indispensable if policy performances are to be measured. Effects of policy performance are measured for key selected AEIs in each study area on the basis of the results of a field survey based on questionnaires of participating and non-participating farmers in the AEP schemes. The main effects may be catalogued as improvement effects or protection effects since they represent a change in participant over non-participant farmers' decisions. Finally, the importance of this type of policy evaluation approach is discussed in the light of the likely future development of AEP in the European Union.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Psychometrika 50 (1985), S. 3-16 
    ISSN: 1860-0980
    Schlagwort(e): Latent correlation ; longitudinal model ; Rasch model ; latent structure analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Psychologie
    Notizen: Abstract A model for longitudinal latent structure analysis is proposed. We assume that test scores for a given mental or attitudinal test are observed for the same individuals at two different points in time. The purpose of the analysis is to fit a model that combines the values of the latent variable at the two time points in a two-dimensional latent density. The correlation coefficient between the two values of the latent variable can then be estimated. The theory and methods are illustrated by a Danish dataset concerning psychic vulnerability.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Computational optimization and applications 10 (1998), S. 243-269 
    ISSN: 1573-2894
    Schlagwort(e): monotone complementarity problem ; homogeneous and self-dual model ; interior-point algorithms ; large-scale convex optimization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract Recently the authors have proposed a homogeneous and self-dual algorithm for solving the monotone complementarity problem (MCP) [5]. The algorithm is a single phase interior-point type method; nevertheless, it yields either an approximate optimal solution or detects a possible infeasibility of the problem. In this paper we specialize the algorithm to the solution of general smooth convex optimization problems, which also possess nonlinear inequality constraints and free variables. We discuss an implementation of the algorithm for large-scale sparse convex optimization. Moreover, we present computational results for solving quadratically constrained quadratic programming and geometric programming problems, where some of the problems contain more than 100,000 constraints and variables. The results indicate that the proposed algorithm is also practically efficient.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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