SB-robust estimator for the concentration parameter of circular normal distribution

In this paper we discuss robust estimation of the concentration parameter (κ) of the circular normal (CN) distribution. It is known that the MLE of the concentration parameter is not B-robust at the family of all circular normal distributions with fixed mean direction (μ) and varying κ > 0. In this paper we propose a new estimator for κ and show that it is B-robust and SB-robust at the family {CN(μ, κ) : m ≤ κ ≤ M} where m and M are two arbitrary constants.     

Comparison of estimators in nested case–control studies with multiple outcomes

Reuse of controls in a nested case-control (NCC) study has not been considered feasible since the controls are matched to their respective cases. However, in the last decade or so, methods have been developed that break the matching and allow for analyses where the controls are no longer tied to their cases. These methods can be divided into two groups; weighted partial likelihood (WPL) methods and full maximum likelihood methods. The weights in the WPL can be estimated in different ways and four estimation procedures are discussed. In addition, we address modifications needed to accommodate left truncation. A full likelihood approach is also presented and we suggest an aggregation technique to decrease the computation time. Furthermore, we generalize calibration for case-cohort designs to NCC studies. We consider a competing risks situation and compare WPL, full likelihood and calibration through simulations and analyses on a real data example.     

Estimating detailed distributions from grouped sociodemographic data: ‘get me started in’ curve fitting using nonlinear models

In much demographic analysis, it is important to know how occurrence-exposure rates or transition probabilities vary continuously by age or by time. Often we have coarse or fluctuating data so there can be a need for estimation and smoothing. Since the distributions of rates or counts across age or another variable are often curved, a nonlinear model is likely to be appropriate. The main focus of this paper is on the estimation of detailed information from grouped data such as age and income bands; however, the methods we outline could also be applied to other settings such as smoothing rates where the original data are ragged. The ability to carry out curve fitting is a very useful skill for population geographers and demographers. Curve fitting is not well covered in statistics textbooks, and whilst there is a large literature in journals thoroughly discussing the detail of functions which define curves, these texts are likely to be inaccessible to researchers who are not specialists in mathematics. We aim here to make nonlinear modelling as accessible as possible. We demonstrate how to carry out nonlinear regression using SPSS, giving stepped-through hypothetical and research examples. We note other software in which nonlinear regression can be carried out, and outline alternative methods of curve fitting.     

Using remote sensing and census tract data to improve representation of population spatial distribution: case studies in the Brazilian Amazon

This work proposes a methodological approach to redistribute population data obtained from polygonal census tracts into population density surfaces (grids) based on a cell space database. The methodology was first developed for the municipality of Marabá, Pará state, in the Brazilian Amazon. We used a dasymetric method to eliminate areas of environmental restriction to human presence; then integrated environmental data indicative of human presence to generate a potential surface of population occurrence; and finally, census population count data were redistributed into cells. The methodology was subsequently adapted for 13 municipalities of the Sustainable Forests District (SFD) of BR-163, generating population distribution surfaces for 2000 and 2007. The evolution of the resident population over the SFD-BR163 showed spatial patterns compatible with the occupation process described in the literature and verified by fieldwork. To be applied over other areas, the proposed methodology must be adapted with local parameters but in this way, population density surfaces can be useful as an additional data source to study population and environment relationships.     

AIDS, “reversal” of the demographic transition and economic development: evidence from Africa

Using country- and region-level data, I investigate the effect of HIV/AIDS on fertility in Africa during 1985–2000. Results differ depending on the variation used and the estimation method. Between estimates that exploit cross-sectional variation suggest a positive significant effect of HIV/AIDS on fertility, whereas within estimates that are identified of off time-series variation show both positive and negative results depending on the HIV/AIDS variable used. These within estimates are insignificant in most of the specifications.     

从一个民族的近代婚姻看理性婚姻的意义

本文通过对纳西族近代婚姻的考察,分析其理性内涵的丰富性、合理性.纳西族近代婚姻是通过对家族经济状况、家庭社会背景、健康状况的综合考察平衡后,经由"父母之命、媒妁之言"缔结的理性婚姻.这种理性婚姻为婚姻的稳定、和满提供了基本条件.本文首次提出"理性婚姻"的概念并指出理性婚姻在一个私有化、现代化社会有其特殊意义.     

汉语简称的分类及其规范

汉语简称是一种较为特殊的语言表达形式,其构成方式也比较多.以往的分类,缺乏统一的标准,结果便不甚理想.本文从简称的构成"原素"及其在全称中的位置两个层次人手,对简称的构成方式进行了重新分类,结果相对严谨合理,界线分明,而且对简称的规范化也有一定意义.     

现代化与中国传统诗学的开新

"现代化"作为20世纪中国文化的套话,深人到中国社会生活的各个层面.中国传统诗学正是在这一背景下遭遇了域外诗学的挑战,并由此规定了现代汉语诗学的路向.本文从外形式到内结构梳理了现代中国诗歌的"现代化"历程,揭示了这一过程中诗学转换的轨迹.     

The Minimal Spanning Tree Preservation Approaches for DNA Multiple Sequence Alignment and Evolutionary Tree Construction

In this paper, we propose a new criterion, namely the minimal spanning tree preservation approach, for both of the DNA multiple sequence alignment and the construction of evolutionary trees. It is our aim to keep the proximity information among the sequences or species via our approach. The basic idea behind this approach is that those distances among species which are close to one another are more informative than the others.