排序方式: 共有37条查询结果,搜索用时 242 毫秒
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This paper is concerned with model selection and model averaging procedures for partially linear single-index models. The profile least squares procedure is employed to estimate regression coefficients for the full model and submodels. We show that the estimators for submodels are asymptotically normal. Based on the asymptotic distribution of the estimators, we derive the focused information criterion (FIC), formulate the frequentist model average (FMA) estimators and construct proper confidence intervals for FMA estimators and FIC estimator, a special case of FMA estimators. Monte Carlo studies are performed to demonstrate the superiority of the proposed method over the full model, and over models chosen by AIC or BIC in terms of coverage probability and mean squared error. Our approach is further applied to real data from a male fertility study to explore potential factors related to sperm concentration and estimate the relationship between sperm concentration and monobutyl phthalate. 相似文献
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Daniela Russ 《Innovation: The European Journal of Social Science Research》2017,30(3):244-258
Recent contributions to a sociological analysis of energy and society focus mostly on its political, economic and technological organization. Yet contrary to other parts of nature, little social scientific attention has been paid to how politics, economics and technology have come to produce and stabilize the concept of energy in the first place and how different natural materials were transformed into “sources of energy.” Drawing from insights of the sociology of comparison, quantification and commensuration, “energy” in this paper is conceived as a “statistical object,” around which a public discourse develops in which comparisons between resources are drawn. Since the beginning of the twentieth century, this discourse has been more and more stabilized by the regular, public production and ever tighter net of elements of comparison, the creation of a highly abstract, potentially quantified point of comparison, and the definition of various criteria tying the compared entities together with more general models and narratives. This theoretical framework is put into practice by an explorative analysis of coal classification in the first quarter of the twentieth century. In this empirical analysis, three fields are identified where coals were “made the same”: engineering, economics and resource statistics. It is shown that the “calorific value” plays an important role for classification in all three fields and, furthermore, constitutes a measure that links coal to other fuels. 相似文献
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J Russ 《Journal of homosexuality》1986,12(3-4):77-87
Willa Cather's early life resembles one of the histories in Jonathan Katz's Gay American History. Her cross-dressing, invention of a male pseudonym, and details of behavior, together with her love for two women in her adulthood, Isabelle McClung and Edith Lewis, make it clear that Cather was a lesbian. Defensive about One of Ours, Cather nonetheless wrote much of her fiction in a male persona--A Lost Lady, The Professor's House, "Tom Outland's Story," Death Comes to the Archbishop, O Pioneers!, My Antonia, and One of Ours, as well as numerous short stories. Much of the fictional material in these works is curiously inconsistent with the male persona, but instead resembles lesbian experiences: the inaccessibility (to the narrator) of women who are nonetheless accessible to other men, absolute heartbreak at the untouchability of the women rather than anger or guilt or the search for sexual release elsewhere, and the women's intimacy with the men involved, as in One of Ours or O Pioneers!, without any suggestion of sexual involvement or explicit sexual history. Lesbian isolation, in adolescence at any rate, produces such situations; Carson McCullers's and some of May Sarton's work are cases in point. Speaking in masquerade, Cather is capable of describing lesbian experience with a fullness and unconsciousness which is now impossible. Innocence gave way to guilty self-consciousness, and that to politically conscious rebellion. The gain is in honesty, but Cather's record of lesbian experience, under whatever disguise, is nonetheless irreplaceable. 相似文献
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汤纯香 《西华师范大学学报(自然科学版)》2000,21(4)
对一只旅居美国的青年雌性大熊猫在休情期和发情期的阴道角化细胞变化作了连续监测.结果表明:休情期间低于35%,发情期间平均高于80%.当角化率上升到70%左右时,提示动物发情期开始;上升至90%左右,表明已进入发情高潮期,是配种良机.其结果与尿激素水平和行为表现相比较,三者具有高度一致性,证明阴道角化细胞变化监测对判定大熊猫的发情及配种时机具有良好的指示意义. 相似文献
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The physical distribution management process involves dual, but conflicting objectives: (1) the minimization of system costs and (2) the maximization of service levels. Most physical distribution research focuses on cost minimization and treats service levels as constraints. This paper, however, highlights the service aspect of distribution. It reports an experiment with purchasing agents designed to test three alternative approaches for evaluating customers' (dollar) trade-offs between service levels received and cost. Two of the approaches indirectly derive trade-off values; the other approach relies on directly reported trade-off information. In this experiment all three of the approaches were quite accurate in modeling customers' preferences for different physical distribution mixes, but the indirect procedures were more accurate than the direct approach. 相似文献
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In this article, we examine the effects of shortcuts in the development of engineered systems through a principal-agent model. We find that occurrences of illicit shortcuts are closely related to the incentive structure and to the level of effort that the agent is willing to expend from the beginning of the project to remain on schedule. Using a probabilistic risk analysis to determine the risks of system failure from these shortcuts, we show how a principal can choose optimal settings (payments, penalties, and inspections) that can deter an agent from cutting corners and maximize the principal's value through increased agent effort. We analyze the problem for an agent with limited liability. We consider first the case where he is risk neutral; we then include the case where he is risk averse. 相似文献
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Russ Vince 《Human Resource Development International》2013,16(4):559-563