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排序方式: 共有101条查询结果,搜索用时 31 毫秒
11.
地处深圳特区的水围村,10年来认真进行经济体制改革,实现了农村经济、社会和文化的均衡发展,成为物质文明和精神文明一起抓、实现“两个转变”(农民变市民,农村变城市)的典型范例。本文着重从农村经济发展道路和发展模式的角度集中分析了水固村的经济发展以及它所给予我们的启示。  相似文献   
12.
在都市报副刊面临“现代化转型”之际,需重新认识其地位与作用,直面其太过庞杂、品格低俗、借“名”逐名、变相广告、湮没个性等现存误区,探讨其走出误区的有效方略,诸如复归自群专刊化、多元兼容个性化、神形深茂杂志化、编读双向互动化、借鉴网络自在化等。  相似文献   
13.
In practical situations involving mixtures formed from several ingredients, interest is sometimes centered on the response in an ellipsoidal neighborhood around a standard formulation. We show that standard, orthogonally blocked, response surface designs, defined on a q ? 1 dimensional unit sphere, may be transformed into similarly orthogonally blocked q-ingredient mixture designs defined within an ellipsoid centered at the standard formulation. The method is illustrated using several examples of mixture experiments with three, four, and five ingredients, arranged in two, three, or four orthogonal blocks, obtained by projecting standard central composite designs and Box–Behnken designs into the ellipsoidal mixture region. Rotations of the resulting designs within the ellipsoidal regions are also considered.  相似文献   
14.
Andrade and Helms (1984) study problems involving estimation and testing of linearly patterned mean and covariance matrices. They parameterize their models under the null hypothesis by using linear constraints on the alternative hypothesis parameterization. In this paper, we show that the nested models that Andrade and Helms consider can be transformed into the nested models considered by Anderson (1969, 1970, 1973) and Szatrowski (1979, 1980, 1981, 1983, 1985).  相似文献   
15.
A substantial part of examining the properties of a distributional family consists of considering shape properties. It is important that this examination is sufficiently thorough to enable understanding of the behaviour of the family, its comparison with others, and to assist in developing future families. The g-and-h distributions and the Johnson system are examined here in these terms  相似文献   
16.
We describe novel, analytical, data-analysis, and Monte-Carlo-simulation studies of strongly heteroscedastic data of both small and wide range.Many different types of heteroscedasticity and fixed or variable weighting are incorporated through error-variance models.Attention is given to parameter bias determinations, evaluations of their significances, and to new ways to correct for bias.The error-variance models allow for both additive and independent power-law errors, and the power exponent is shown to be able to be well determined for typical physicalsciences data by the rapidly-converging, general-purpose, extended-least-squares program we use.The fitting and error-variance models are applied to both low-and high-heteroscedasticity situations, including single-response data from radioactive decay.Monte-Carlo simulations of data with similar parameters are used to evaluate the analytical models developed and the various minimization methods em-ployed, such as extended and generalized least squares.Logarithmic and inversion transformations are investigated in detail, and it is shown analytically and by simulations that exponential data with constant percentage errors can be logarithmically transformed to allow a simple parameter-bias-removal procedure.A more-general bias-reduction approach combining direct and inversion fitting is also developed.Distributions of fitting-model and error-variance-model parameters are shown to be typically non-normal, thus invalidating the usual estimates of parameter bias and precision.Errors in conventional confidence-interval estimates are quantified by comparison with accurate simulation results.  相似文献   
17.
Although there is no shortage of clustering algorithms proposed in the literature, the question of the most relevant strategy for clustering compositional data (i.e. data whose rows belong to the simplex) remains largely unexplored in cases where the observed value is equal or close to zero for one or more samples. This work is motivated by the analysis of two applications, both focused on the categorization of compositional profiles: (1) identifying groups of co-expressed genes from high-throughput RNA sequencing data, in which a given gene may be completely silent in one or more experimental conditions; and (2) finding patterns in the usage of stations over the course of one week in the Velib' bicycle sharing system in Paris, France. For both of these applications, we make use of appropriately chosen data transformations, including the Centered Log Ratio and a novel extension called the Log Centered Log Ratio, in conjunction with the K-means algorithm. We use a non-asymptotic penalized criterion, whose penalty is calibrated with the slope heuristics, to select the number of clusters. Finally, we illustrate the performance of this clustering strategy, which is implemented in the Bioconductor package coseq, on both the gene expression and bicycle sharing system data.  相似文献   
18.
Based on Stein’s famous shrinkage estimation of a multivariate normal distribution, we propose a new type of estimators of the distribution function of a random variable in a nonparametric setup. The proposed estimators are then compared with the empirical distribution function, which is the best equivariant estimator under a well-known loss function. Our extensive simulation study shows that our proposed estimators can perform better for moderate to large sample sizes.  相似文献   
19.
中国农村地区的家庭禀赋与外出务工劳动力回流   总被引:5,自引:0,他引:5  
中国农村地区家庭禀赋对个人的行为决策有着重要的影响,需要学术界予以更多的关注。为了考察外生性的家庭禀赋对劳动力就业流动的影响,文章通过构建新生代外出务工劳动力和户主子女的回流决策两个计量模型来进行经验论证。分析结果表明,农村劳动力的迁移选择是综合考虑家庭禀赋状况的理性决策,尤其是对于年轻一代的外出劳动力。家庭经济资本的增加会阻碍家庭外出务工成员的回流。外出劳动力回流的概率起初随着家庭人力资本和家庭自然资本的增长而上升,达到一定程度后开始下降。家庭成员只有拥有较为丰富的人力资本,外出务工劳动力才能对家庭社会资本加以充分利用。另外,分析显示年轻一代劳动力和第一代劳动力对家庭社会资本和自然资本的利用是有差异的。  相似文献   
20.
过去30年间深圳市的经济发展取得了举世瞩目的成就,特别是在1978年改革开放以后,深圳市正在经历由传统农业社会向现代工业社会转型、再分配经济向市场经济转轨的过程,由此导致阶层结构的变化。按经济分层来看,贫困人口不断减少,中产阶层出现并且其规模迅速扩大。本文以家庭为单位,利用国家统计局组织的中国城镇住户调查中的深圳市样本1988—2009年22年的数据分析中产阶层家庭规模比重变化、中产阶层家庭户主的年龄结构、性别结构、教育结构、组织特征以及行业结构的变化。  相似文献   
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