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Complete Population (complete + population)

Distribution by Scientific Domains

Humanities and Social Sciences	75%

Selected Abstracts

Population Synthesis: Comparing the Major Techniques Using a Small, Complete Population of Firms

GEOGRAPHICAL ANALYSIS, Issue 2 2009
Justin Ryan
Recently, disaggregate modeling efforts that rely on microdata have received wide attention by scholars and practitioners. Synthetic population techniques have been devised and are used as a viable alternative to the collection of microdata that normally are inaccessible because of confidentiality concerns or incomplete because of high acquisition costs. The two most widely discussed synthetic techniques are the synthetic reconstruction method (IPFSR), which makes use of iterative proportional fitting (IPF) techniques, and the combinatorial optimization (CO) method. Both methods are described in this article and then evaluated in terms of their ability to recreate a known population of firms, using limited data extracted from the parent population of the firms. Testing a synthetic population against a known population is seldom done, because obtaining an entire population usually is too difficult. The case presented here uses a small, complete population of firms for the City of Hamilton, Ontario, for the year 1990; firm attributes compiled are number of employees, 3-digit standard industrial classification, and geographic location. Results are summarized for experiments based upon various combinations of sample size and tabulation detail designed to maximize the accuracy of resulting synthetic populations while holding input data costs to a minimum. The output from both methods indicates that increases in sample size and tabulation detail result in higher quality synthetic populations, although the quality of the generated population is more sensitive to increases in tabular detail. Finally, most tests conducted with the created synthetic populations suggest that the CO method is superior to the IPFSR method. Los modelos desagregados basados en micro data han recibido la atención relativamente reciente de los círculos académicos y de aplicación. La colección de dicha data es una tarea difícil por cuestiones de accesibilidad, confidencialidad, datos incompletos o altos costos de adquisición. Por esta razón se han creado indicadores sintéticos como a alternativa a la recolección directa de datos. Los dos indicadores sintéticos mas discutidos/conocidos son el método de Reconstrucción Sintética (Sytnthetic Reconstruction method) (IPFSR) que hace uso de técnicas de Ajuste Proporcional Iterativo (IPF); y el método Optimización Combinatoria (CO). Ambos métodos son descritos en este artículo y luego evaluados en base a su habilidad de recrear una población de empresas ya conocidas o preestablecidas. Contrastar una población sintética versus una población conocida es una operación poco frecuente porque la obtención de una población entera es por lo general bastante difícil. El caso presentado en este estudio utiliza una población pequeña y completa de empresas en la ciudad de Hamilton, Ontario (Canadá) para el año 1990. Las variables recopiladas son el número de empleados, SIC (código estandarizado de clasificación industrial), y ubicación geográfica. Los resultados que se reportan en el presente estudio son producto de varios experimentos basados en varias combinaciones del tamaño de la muestra, y del detalle en la tabulación diseñados, los mismos que fueron diseñados para maximizar la exactitud de las poblaciones sintéticas calculadas y al mismo tiempo minimizar los costos de datos necesarios. Los resultados obtenidos por ambos métodos indica que los incrementos en el tamaño de la muestra y en el detalle de la tabulación resultan en un estimado de poblaciones mejor, aunque este estimado es particularmente sensible a incrementos en el detalle de las tabulaciones. Finalmente, la mayoría de pruebas realizadas con las poblaciones sintéticas generadas para este estudio sugieren que el método CO es superior al método IPFSR. [source]

Technical efficiency and embodied technical change in the Indonesian pulp and paper industry

JOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 2 2006
Michiel Van Dijk
Abstract In this paper the dynamics of technological change and technical efficiency in the Indonesian pulp and paper industry are analysed. The industry is characterised by rapid growth of output and capacity, with some mills investing heavily in state-of-the-art machinery after 1984. Using stochastic frontier analysis, we distinguish between technological advances of best practice mills and the rate of technological inefficiency. We use a newly constructed micro-level dataset describing the complete population of Indonesian paper mills and paper machines from 1975 to 1997. We find an increasing divergence in technical efficiency over time, indicating that most plants have been not able to keep up with the technological leaders in the industry. Several of the plants operating the latest technologies have lower levels of efficiency than mills operating more outdated equipment. These outcomes qualify the common understanding of dualistic economic structures in developing countries, composed of less efficient traditional and more efficient modern capital intensive establishments. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Effect of the Rht-D1 dwarfing locus on Fusarium head blight rating in three segregating populations of winter wheat

PLANT BREEDING, Issue 4 2008
H.-H. Voss
Abstract Fusarium head blight (FHB) is one of the major fungal diseases in wheat throughout the world. To control FHB severity, breeding genetically resistant varieties is thought to be the most promising strategy. In wheat breeding programmes, short cultivars predominantly carrying the Norin 10 derived semi-dwarfing allele Rht-D1b (Rht2) are preferred worldwide because of higher achievable grain yields and lower risk of lodging. This study was conducted to determine the influence of different alleles at the Rht-D1 locus on FHB reaction. Three winter wheat populations were produced by crossing rather susceptible varieties ,Biscay', ,Pirat' and ,Rubens' carrying mutant-type allele Rht-D1b with the more resistant varieties ,Apache', ,Romanus' and ,History' containing the Rht-D1a wild-type allele (rht2). The 190, 216 and 103 progeny of the F4 -derived populations were assayed for the presence of Rht-D1a or Rht-D1b, plant height, and mean FHB rating after spray inoculation at flowering time with a highly aggressive isolate of Fusarium culmorum. Comparably, high mean FHB severities ranging from 28% to 49% for all population × environment combinations were achieved, with significant genotypic variation for FHB rating and plant height within all populations. Both traits were negatively correlated with r ranging from ,0.48 to ,0.61 in the complete populations. However, within the subpopulations homozygous for one or other height allele these correlations decreased considerably. The Rht-D1b semi-dwarfing allele resulted in 7,18% shorter plants, depending on the population, but a considerably increased FHB reaction of 22,53%. Nevertheless, significant genotypic variance for FHB resistance remained in all tested Rht-D1b subpopulations indicating that selection for moderately FHB resistant genotypes within agronomically beneficial Rht-D1b genotypes is still feasible. [source]