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991.
Examining the impact of context on individual‐level outcomes has become an increasingly common undertaking in the social sciences. The growth in concern for identifying the effects of macrolevel characteristics has generated both theoretical and methodological advancements. In this issue of Journal of Marriage and Family, Butler (2002) researches whether the effect of welfare benefit levels on premarital childbearing varies by context, Hoffmann (2002) researches the effect of context on adolescent drug use, and Simons et al. (2002) examine how the relationship between parenting and child conduct varies by context. These articles are used as a background to discuss important theoretical and methodological issues surrounding the analysis of multilevel data. The authors present a simple analysis of data pertaining to age at first marriage taken from the Panel Study of Income Dynamics and merged with census data to measure contextual effects as a pedagogical device for introducing readers to the benefits of multilevel modeling. 相似文献
992.
The authors consider the problem of simple linear regression when the exogenous and endogenous variables are functional and the design is fixed. They propose an estimator for the underlying linear operator and prove its consistency under some conditions which ensure that the design is sufficiently informative. They consider the classical calibration (or inverse regression) problem and analyze a consistent estimator. They also give a simulation study. The proposed method is not hard to implement in practice. 相似文献
993.
讨论信号方向偏离约束方向(即信号方向误差)对线性约束自适应阵性能的影响.把输出信噪比看作是信号方向和输入信噪比的函数,研究了输出信噪比同信号方向和输入信噪比的关系.通过分析,结果发现在一定的输入信噪比下,要求的输出信噪比越大,信号方向误差就应越小;对具有一定方向误差的信号,输入信噪比越大,有用信号受到的抑制就越厉害;当干扰信号存在时,阵对信号方向误差的敏感度减少. 相似文献
994.
Kiyoshi Inoue 《Journal of statistical planning and inference》2003,110(1-2):133-146
The aim of this study is to improve the efficiency of weighted least-squares estimates for a regression parameter. An iterative procedure, starting with an unbiased estimate other than the unweighted least-squares estimate, yields estimates which are asymptotically more efficient than the feasible generalized least-squares estimate when errors are spherically distributed. The result has an application in the improvement of the Graybill–Deal estimate of the common mean of several normal populations. 相似文献
995.
Arthur Renshaw Steven Haberman 《Journal of the Royal Statistical Society. Series C, Applied statistics》2003,52(1):119-137
Summary. The paper presents a reinterpretation of the model underpinning the Lee–Carter methodology for forecasting mortality (and other vital) rates. A parallel methodology based on generalized linear modelling is introduced. The use of residual plots is proposed for both methods to aid the assessment of the goodness of fit. The two methods are compared in terms of structure and assumptions. They are then compared through an analysis of the gender- and age-specific mortality rates for England and Wales over the period 1950–1998 and through a consideration of the forecasts generated by the two methods. The paper also compares different approaches to the forecasting of life expectancy and considers the effectiveness of the Coale–Guo method for extrapolating mortality rates to the oldest ages. 相似文献
996.
《线性代数》课程教学改革的实践与思考 总被引:5,自引:0,他引:5
从线性代数课程的教学现状、内容结构,现行教材的体系为出发点,在课程体系、教学内容等方面提出了在注重经典理论内容的同时,应渗透现在教学的观念、思想和方法.在教学方法和教学手段方面阐明了运用启发式教学方法以及穿透教学手段和多媒体教学手段相结合的意义和作用,提出了一些教学改革的建议. 相似文献
997.
998.
赖会娣 《华北工学院学报(社会科学版)》2013,(6):92-96,102
在国际化大好形势下,汉文化的丰富语言亟待“以我为主”的本土化研究。“非真诚拒绝”作为一种既普遍又特殊的言语行为,从其定义、条件、特征,及间接性、适切条件和意向性等维度分析,都证明了具有中国特色的此类虚假性言语行为在奥斯汀、塞尔等处享有厚实的语言哲学根基,富有研究意义。 相似文献
999.
NAN LI 《Mathematical Population Studies》2013,20(2):105-116
Population momentum is the ratio of a population's ultimate size after a demographic transition to its initial size before the transition. For stable population and instantaneous drop to replacement fertility, Keyfitz found a simple formula for the momentum. Although Keyfitz's formula has been extended to cover gradual demographic transitions, the stable initial population, however, is still an obstacle to approaching reality. Using the solution of the Lotka equation with time-varying vital rates and extending it to negative values of time, exact and accurate formulae for the momentum of any initial population that undergoes a linear fertility transition are expressed. Examples using the data from the United Nations indicate that the accurate formula works well for the age structures that are far from stable such as the more and less developed regions, as well as that close to stable such as the least developed region. 相似文献
1000.