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51.
This paper presents a new shift-share model to decompose the employment growth rate of a territorial unit by taking into consideration the association between industry mix and firm legal status effects measured in its neighborhood. We explicitly consider this kind of association to go beyond the problem of asymmetry found in a previous work. The empirical application refers to the data collected in the Italian Business Statistical Register and, in particular, regional employment figures in Friuli Venezia Giulia (NUTS2 level), for 219 territorial units (LAU2 level) and 12 Local Labour Systems (LLS), for the years 2001 and 2004. 相似文献
52.
We apply the well known Gini index to the measurement of concentration in survival times within groups of patients, and as a way to compare the distribution of survival times across groups of patients in clinical studies. In particular, we propose an estimator of a restricted version of the index from right censored data. We derive the asymptotic distribution of the resulting Gini statistic, and construct an estimator for its asymptotic variance. We use these results to propose a novel test for differences in the heterogeneity of survival distributions, which may suggest the presence of a differential treatment effect for some groups of patients. We focus in particular on traditional and generalized cure rate models, i.e., mixture models with a distribution of the lifetimes of the cured patients that is either degenerate at infinity or has a density. Results from a simulation study suggest that the Gini index is useful in some situations, and that it should be considered together with existing tests (in particular, the Log-rank, Wilcoxon, and Gray–Tsiatis tests). Use of the test is illustrated on the classic data arising from the Eastern Cooperative Oncology Group melanoma clinical trial E1690. 相似文献
53.
Existence and consistency of the Maximum Likelihood estimator of the parameters of heterogeneous mixtures of Gaussian and uniform distributions with known number of components are shown under constraints to prevent the likelihood from degeneration and to ensure identifiability. The EM-algorithm is discussed, and for the special case with a single uniform component a practical scheme to find a good local optimum is proposed. The method is compared theoretically and empirically to the estimation of a Gaussian mixture with “noise component” as introduced by Banfield and Raftery (1993) to find out whether it is a worthwhile alternative particularly in situations with outliers and points not belonging to the Gaussian components. 相似文献
54.
We explore the possibility of approximating the Ferguson-Dirichlet prior and the distributions of its random functionals through the simulation of random probability measures. The proposed procedure is based on the constructive definition illustrated in Sethuraman (1994) in conjunction with the use of a random stopping rule. This allows us to set in advance the closeness to the distributions of interest. The distribution of the stopping rule is derived, and the practicability of the simulating procedure is discussed. Sufficient conditions for convergence of random functionals are provided. The numerical applications provided just sketch the idea of the variety of nonparametric procedures that can be easily and safely implemented in a Bayesian setting. 相似文献
55.
Gian Pietro Zaccomer 《Transition Studies Review》2008,15(1):111-123
In a previous work, a spatial shift-share model was proposed. That model took into account both the activity information of
the territory and the legal status of the enterprises working inside it. The model presented, which had a twofold form, developed
and came together into a unique formulation. The present proposal is able to suitably catch the neighborhood’s effect on the
variation of an economical variable measured on the examined territory. This paper does not intend to repropose the aspects
regarding the theoretical evolution of the first model. Instead, the principal goal is to make a comparison ceteris paribus
between the results obtained with the new model and those reached through the application of the previous one, so to highlight
the role of the association between the two factors included inside the decomposition. Italian industrial districts represent
the economical context for this application since each model proposed is applicable to each district case without modifying
the theoretical structure which is related, to the neighborhood definition. The application proposed here focuses on data
on the chair industrial district located in the border region Friuli Venezia Giulia, with reference to the entire period 2000–2004. 相似文献
56.
Summary Let {X
n
} be a sequence of random variables conditionally independent and identically distributed given the random variable Θ. The
aim of this paper is to show that in many interesting situations the conditional distribution of Θ, given (X
1,…,X
n
), can be approximated by means of the bootstrap procedure proposed by Efron and applied to a statisticT
n
(X
1,…,X
n
) sufficient for predictive purposes. It will also be shown that, from the predictive point of view, this is consistent with
the results obtained following a common Bayesian approach. 相似文献
57.
Event-related brain potentials (ERPs) were studied in subjects deprived of sleep over a 48-h test period to assess the effects of different durations of continuous wakefulness on ERP components and to determine whether changes in the ERP components were related to changes in performance. Forty subjects were randomly assigned to either an experimental (sleep deprived) group (n = 30) or a control (not sleep deprived) group (n = 10). For the experimental subjects, ERP and performance measures were obtained in four-h test blocks throughout the 48-h period. Performance was assessed using the Walter Reed performance assessment battery. The control subjects were tested at the same times except during designated sleep periods. Both performance and evoked potential measures showed systematic changes over the experimental test period in association with sleep deprivation, time of day, and repeated testing. The latency of the N2 component of the evoked potential covaried with throughput measures on the performance assessment battery across the 12 four-h test blocks of the experiment. These data suggest that ERPs reflect central processes that change across the sleep deprivation period and that ERP measures might be useful in assessment and prediction of performance degradation under adverse conditions such as sleep loss. 相似文献
58.
Pietro Muliere & Stephen Walker 《Journal of the Royal Statistical Society. Series B, Statistical methodology》1998,60(1):175-182
A Bayesian bootstrap for a finite population with censored observations is introduced. It is shown to reduce to the finite population Bayesian bootstrap if there is no censoring and to reduce to the censored data Bayesian bootstrap for a large population. A class of general urn schemes for simulating exchangeable sequences of variables is introduced which is connected to the bootstrap method. 相似文献
59.
What drives progressive public policy? Because progressive policy challenges the interests of powerful people and interests that dominate policy making, it is puzzling that progressive policy ever happens. This article addresses this question by modeling and appraising institutional political, political mediation, and policy feedback theories and models of progressive policy making. Institutional political theory focuses on political institutional conditions, bureaucratic development, election results, and public opinion. Political mediation theory holds that social movements can have influence over progressive policy under favorable political conditions. Policy feedback theory holds that programs will be self‐reinforcing under certain conditions. The article goes beyond previous research by including and analyzing public opinion in institutional political and political mediation models and addressing positive policy feedbacks. We appraise five models derived from these three theories through fuzzy set qualitative comparative analyses of the generosity of early old‐age policy across U.S. states at two key moments. We find some support for each theory, and the results suggest that they are complementary. Left regimes or social movements can initiate progressive policy, which can be reinforced for the long term through positive policy feedback mechanisms. We discuss the implications for current U.S. politics and for progressive policy elsewhere. 相似文献
60.
Abstract. It is well known that Jeffreys' prior is asymptotically least favorable under the entropy risk, i.e. it asymptotically maximizes the mutual information between the sample and the parameter. However, in this paper we show that the prior that minimizes (subject to certain constraints) the mutual information between the sample and the parameter is natural conjugate when the model belongs to a natural exponential family. A conjugate prior can thus be regarded as maximally informative in the sense that it minimizes the weight of the observations on inferences about the parameter; in other words, the expected relative entropy between prior and posterior is minimized when a conjugate prior is used. 相似文献