排序方式: 共有31条查询结果,搜索用时 15 毫秒
1.
Nonparametric Estimation of the Number of Drug Users in Hong Kong Using Repeated Multiple Lists
下载免费PDF全文
![点击此处可从《Australian & New Zealand Journal of Statistics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Richard M. Huggins Paul S.F. Yip Jakub Stoklosa 《Australian & New Zealand Journal of Statistics》2016,58(1):1-13
We update a previous approach to the estimation of the size of an open population when there are multiple lists at each time point. Our motivation is 35 years of longitudinal data on the detection of drug users by the Central Registry of Drug Abuse in Hong Kong. We develop a two‐stage smoothing spline approach. This gives a flexible and easily implemented alternative to the previous method which was based on kernel smoothing. The new method retains the property of reducing the variability of the individual estimates at each time point. We evaluate the new method by means of a simulation study that includes an examination of the effects of variable selection. The new method is then applied to data collected by the Central Registry of Drug Abuse. The parameter estimates obtained are compared with the well known Jolly–Seber estimates based on single capture methods. 相似文献
2.
Matthias Neumann Christian Hirsch Jakub Stank Viktor Bene Volker Schmidt 《Scandinavian Journal of Statistics》2019,46(3):848-884
We investigate the problem of estimating geodesic tortuosity and constrictivity as two structural characteristics of stationary random closed sets. They are of central importance for the analysis of effective transport properties in porous or composite materials. Loosely speaking, geodesic tortuosity measures the windedness of paths, whereas the notion of constrictivity captures the appearance of bottlenecks resulting from narrow passages within a given materials phase. We first provide mathematically precise definitions of these quantities and introduce appropriate estimators. Then, we show strong consistency of these estimators for unboundedly growing sampling windows. In order to apply our estimators to real data sets, the extent of edge effects needs to be controlled. This is illustrated using a model for a multiphase material that is incorporated in solid oxide fuel cells. 相似文献
3.
A graph is locally irregular if the neighbors of every vertex v have degrees distinct from the degree of v. A locally irregular edge-coloring of a graph G is an (improper) edge-coloring such that the graph induced on the edges of any color class is locally irregular. It is conjectured that three colors suffice for a locally irregular edge-coloring. In the paper, we develop a method using which we prove four colors are enough for a locally irregular edge-coloring of any subcubic graph admiting such a coloring. We believe that our method can be further extended to prove the tight bound of three colors for such graphs. Furthermore, using a combination of existing results, we present an improvement of the bounds for bipartite graphs and general graphs, setting the best upper bounds to 7 and 220, respectively. 相似文献
4.
Guy Abel Jakub Bijak Allan Findlay David McCollum Arkadiusz Wiśniowski 《Population and environment》2013,35(2):183-203
Over the next 50 years, the potential impact of environmental change on human livelihoods could be considerable, with one possible consequence being increased levels of human mobility. This paper explores how uncertainty about the level of immigration to the United Kingdom as a consequence of environmental factors elsewhere may be forecast using a methodology involving Bayesian models. The conceptual understanding of forecasting is advanced in three ways. First, the analysis is believed to be the first time that the Bayesian modelling approach has been attempted in relation to environmental mobility. Second, the paper considers the expediency of this approach by comparing the responses to a Delphi survey with conventional expectations about environmental mobility in the research literature. Finally, the values and assumptions of the expert evidence provided in the Delphi survey are interrogated to illustrate the limited set of conditions under which forecasts of environmental mobility, as set out in this paper, are likely to hold. 相似文献
5.
6.
7.
The threat that domestic cats pose to wildlife has gained increased recognition by researchers and conservationists, and in this study, we investigated the seasonal variability and the effects of environment type (rural vs. urban) on the prey composition of free-ranging house cats in Poland. We analysed the variability in 307 monthly prey samples of different prey items killed by cats and brought to their owners (i.e., prey brought home by cats living in one home in one month) between 2002 and 2007 at 26 rural and urban sites. The variability in prey composition over time was analysed using additive models and canonical correspondence analysis. In total, we recorded 1348 prey items. Rodents were the most common prey in both environments, but shrews and reptiles were killed by cats more often in the rural environment while birds (mainly sparrows and pigeons) were more common in the urban environment. Additionally, prey composition changed seasonally. The pooled number of vertebrates killed by cats was largest in September and lowest in January, and rodents were killed most often in September, shrews and birds in June, and reptiles in April. The seasonal variation in the prey composition of cats was relatively high in the rural environment and more stable in the urban environment. Prey composition seemed to follow temporal and spatial variations in prey availability, thus confirming a facultative feeding strategy in free-ranging house cats. 相似文献
8.
9.
Jakub Kazecki 《Canadian Slavonic papers》2013,55(4):449-467
The writing of Radek Knapp, a Polish-born author writing in German, is singular among the works of immigrant writers in the German-speaking countries for his nostalgic yet satirical view of Poland from the perspective of a long-time immigrant to Austria who understands both worlds well. The author, born in Warsaw in 1964 and living in Vienna since 1976, uses predominantly humoristic strategies to expose the national stereotypes that determine and undermine the contacts between Austrians, Germans, and Poles and shape the images of the foreigner in each of the countries. From this point of view, Knapp’s latest work, Gebrauchsanweisung für Polen [Instruction Manual for Poland, 2005], can be read as a work complementing his previous novel, Herrn Kukas Empfehlungen [Mr. Kuka’s Recommendations, 1999], in which, in a similarly humoristic style, he depicts the first encounters of a Polish high-school graduate with the idealized Western world.The article concentrates on Knapp’s use of humour in the depictions of foreigners in Austria and Germany on the one hand and Poland on the other. Using humour theories based on incongruity and surprise as conditions for a humorous effect to take place, the article investigates how comic strategies are employed in Knapp’s works to create a ‘laughter community’ of readers thinking beyond and across borders. 相似文献
10.
The paper is concerned with the everyday manifestation of increasing social, lifestyle and cultural diversity in the transforming inner city of Prague. The Smíchov neighbourhood and particularly its central hub, the Anděl junction, were chosen as the focus of the study. The regeneration dynamics during the post-socialist transformation make this place particularly interesting for an inquiry into the interplay of the social and physical environment, into the interactions of changing urban landscapes and people's everyday practices. Particular attention is paid to the character of ordinary daily street life, to the users of urban space and to the manifestation of close-knit social, spatial and temporal diversity in the close vicinity of the Anděl hub. The paper concludes with the necessity of including the temporal dimension of space in urban planning and design practice. Methodologically the case study derives principally from direct observation of neighbourhood life and users, but also draws on the extensive research previously conducted in the neighbourhood by the authors and from intensive experience of living in the area. 相似文献