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91.
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93.
Combining Sample and Census Data in Small Area Estimates: Iterative Proportional Fitting with Standard Software* 总被引:1,自引:0,他引:1
The combination of detailed sample data with less detailed but fully enumerated marginal subtotals is the focus of a wide range of research. In this article we advocate careful modeling of sample data, followed by Iterative Proportional Fitting (IPF). The modeling aims to estimate accurately the interaction or odds ratios of complex tables, which is information not contained in the marginal subtotals. IPF ensures consistency with the subtotals. We advance this work in three practical ways. First, we show that detailed small‐area estimates of both counts and proportional distributions usually gain accuracy by combining data for larger areas containing the small areas, and we illustrate the multilevel framework to achieve these estimates. Second, we find that a general classification or socioeconomic typology of the small areas is even more associated with the within‐area interactions than is membership of the larger area. Third, we show how the Statistical Package for the Social Sciences (SPSS) can be used for IPF in any number of dimensions and with any structure of constraining marginal subtotals. Throughout, we use an example taken from the 1991 U.K. Census. These data allow us to evaluate various methods combining 100 percent tabulations and the Samples of Anonymised Records. 相似文献
94.
近年来,神农架松柏镇居民的结石病时有发生.并有增长的势头。为了解地质环境尤其是饮用水对病患的影响,笔者现场对患病情况以及各种水源(包括河水、泉水、自来水)的来源、化学组成和放射性进行了调查,运用水质常规方法和原子吸收光谱分别测定了离子和微量元素。同时,与地质环境类似的木鱼镇进行了对比调查。研究结果显示,两地地表水、地下水的各种指标均未超出“生活饮用水水源水质卫生标准”。(CJ3020-93),且松柏镇水体中的放射性(γ射线)低于木鱼镇,而居民的患病率却远高于木鱼镇,可见松柏镇的水环境与居民的结石病无直接关系。 相似文献
95.
This paper proposes a non‐iterative time integration (NITI) scheme for non‐linear dynamic FEM analysis. The NITI scheme is constructed by combining explicit and implicit schemes, taking advantage of their merits, and enables stable computation without an iteration process for convergence even when used for non‐linear dynamic problems. Formulation of the NITI scheme is presented and its stability is studied. Although the NITI scheme is not unconditionally stable when applied to non‐linear problems, it is stable in most cases unless stiffness hardening occurs or the problem has a large velocity‐dependent term. The NITI scheme is applied to dynamic analysis of the non‐linear soil–structure system and computation results are compared with those by the central difference method (CDM). Comparison shows that the stability of the NITI scheme is superior to that of the CDM. Accuracy of the NITI scheme is verified because its results are identical with those by the CDM in which the time step is set as 1/10 of that for the NITI scheme. The application of the NITI scheme to the mesh‐partitioned FEM is also proposed. It is applied to dynamic analysis of the linear soil–structure system. It yields the same results as a conventional single‐domain FEM analysis using the Newmark β method. This result verifies the usability of mesh‐partitioned FEM analysis using the NITI scheme. Copyright © 2003 John Wiley& Sons, Ltd. 相似文献
96.
97.
Mean orbital elements are obtained from osculating ones by removing the short periodic perturbations. Large catalogues of
asteroid mean elements need to be computed, as a first step in the computation of proper elements, used to study asteroid
families. The algorithms for this purpose available so far are only accurate to first order in the masses of the perturbing
planet; the mean elements have satisfactory accuracy for most of the asteroid belt, but degraded accuracy in the neighbourhoods
of the main mean motion resonances, especially the 2:1. We investigate a number of algorithms capable of improving this approximation;
they belong to the two classes of Breiter-type methods and iterative methods. The former are obtained by applying some higher
order numerical integration scheme, such as Runge–Kutta, to the differential equation whose solution is a transformation removing
the fast angular variables from the equations; they can be used to compute a full second order theory, however, only if the
full second order determining function is explicitly computed, and this is computationally too cumbersome for a complicated
problem such as the N-body. The latter are fixed point iterative schemes, with the first order theory as an iteration step,
used to compute the inverse map from mean to osculating elements; formally the method is first order, but because they implement
a fixed frequency perturbation theory, they are more accurate than conventional single iteration methods; a similar method
is already in use in our computation of proper from mean elements. Many of these methods are tested on a sample of asteroid
orbits taken from the Themis family, up to the edge of the 2:1 resonance, and the dispersion of the values of the computed
mean semimajor axis over 100 000 years is used as quality control. The results of these tests indicate that the iterative
methods are superior, in this specific application, to the Breiter methods, in accuracy and reliability. This is understood
as the result of the cancellations occurring between second order perturbation terms: the incomplete second order theory,
resulting from the use of a Breiter method with the first order determining function only, can be less accurate than complete,
fixed frequency theories of the first order. We have therefore computed new catalogues of asteroid mean and proper elements,
incorporating an iterative algorithm in both steps (osculating to mean and mean to proper elements). This new data set, significantly
more reliable even in the previously degraded regions of Themis and Cybele, is in the public domain.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
98.
OnthecolocationiterativesolutionmodelandalgorithmforgravityanomalyYUAN-XIYANG(杨元喜)andCHANG-JIANLIU(刘长建)ZhengzhouInstituteofS... 相似文献
99.
卢冈 《武汉大学学报(信息科学版)》1987,(3)
本文根据稳健估计的一般原理,提出了稳健S-变换的概念,导出了其内制约法迭代解法。并对各种稳健S-变换确定位移场的优劣及有效性进行了验证,得出了一些有益的结论。 相似文献
100.
1IntroductionSongbaiTown—thecapitaloftheShengnongjiaforestdistrictisthecenteroflocalpolitics,eco nomicsandculture ,anditisalsoanimportanttourismbase.Butinrecentyears,thelocalinhabi tantsinthisareahavesufferedfromcalculusdiseaseoccasionallyandthediseaseseemstobeofmoreandmorefrequentoccurrence .Thisnotonlycausesmasspanicandinfluencesnormalworkandstudyofthelocalpeople ,butalsobringsaboutnegativeeffectsontouristindustryofthisareaandrestrictsthedevelopmentoflocaleconomy .Inordertounderstandthesta… 相似文献