排序方式: 共有86条查询结果,搜索用时 15 毫秒
51.
Büşra Sevinç Selma Gürler Bekir Çetintav 《Journal of Statistical Computation and Simulation》2018,88(14):2799-2810
Ranked set sampling (RSS) is an advanced sampling method which is very effective for estimating mean of the population when exact measurement of observation is difficult and/or expensive. Balanced Groups RSS (BGRSS) is one of the modification of RSS where only the lowest, the median and the largest ranked units are taken into account. Although BGRSS is advantageous and useful for some specific cases, it has strict restrictions regarding the set size which could be problematic for sampling plans. In this study, we make an improvement on BGRSS and propose a new design called Partial Groups RSS which offers a more flexible sampling plan providing the independence of the set size and sample size. Partial Groups RSS also has a cost advantage over BGRSS. We construct a Monte Carlo simulation study comparing the performance of the mean estimators of the proposed sampling design and BGRSS according to their sampling costs and mean squared errors for various type of distributions. In addition, we give a biometric data application for investigating the efficiency of Partial Groups RSS in real life applications. 相似文献
52.
We provide a test of the impact of voters' political ideology on economic growth and of the role of preferences for government size as a transmission channel. We focus on France from the beginning of its stable democratic experience in 1871. A move of voters' ideology to the right increases economic growth over the total observation period. However, the growth effect of ideology is mediated by voters' preferences for government size only during the post‐World War II period. For reverse causality concerns, we use the political ideology of other historical democracies as an instrument variable for France's ideology. (JEL E6, O43, H11) 相似文献
53.
Les auteurs examinent l'évolution des tâches accomplies par les travailleurs au Royaume‐Uni entre 1997 et 2006, qu'elle soit due à une reconfiguration des professions elles‐mêmes (marge intensive) ou à une variation de leur part respective dans l'emploi (marge extensive). Ils se fondent notamment dans cet examen sur des données de la Skills Survey, enquête britannique sur les compétences. Leur analyse montre que la variation à la marge intensive est notable et aussi importante que la variation à la marge extensive. Une analyse économétrique fait ressortir en outre que le progrès technique joue un rôle dans l'évolution à la marge intensive, mais pas les délocalisations. 相似文献
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Given a directed graph G=(N,A) with arc capacities u
ij
and a minimum cost flow problem defined on G, the capacity inverse minimum cost flow problem is to find a new capacity vector
[^(u)]\hat{u}
for the arc set A such that a given feasible flow
[^(x)]\hat{x}
is optimal with respect to the modified capacities. Among all capacity vectors
[^(u)]\hat{u}
satisfying this condition, we would like to find one with minimum
||[^(u)]-u||\|\hat{u}-u\|
value.
We consider two distance measures for
||[^(u)]-u||\|\hat{u}-u\|
, rectilinear (L
1) and Chebyshev (L
∞) distances. By reduction from the feedback arc set problem we show that the capacity inverse minimum cost flow problem is
NP\mathcal{NP}
-hard in the rectilinear case. On the other hand, it is polynomially solvable by a greedy algorithm for the Chebyshev norm.
In the latter case we propose a heuristic for the bicriteria problem, where we minimize among all optimal solutions the number
of affected arcs. We also present computational results for this heuristic. 相似文献
56.
Çağatay Çetinkaya 《统计学通讯:理论与方法》2018,47(17):4311-4328
The standard two-sided power distribution is a flexible distribution having uniform, power function and triangular as subdistributions, and it is a reasonable alternative to the Laplace distribution in some cases. In this work, computationally efficient expressions for moments of order statistics, expressions for L-moments, and asymptotic results for sample extrema are derived. Then a simulation study is performed for the location-scale estimation problem of a small data set by considering the maximum likelihood estimation method and the best linear unbiased estimation method based on the moments of order statistics. 相似文献
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The US National Academy of Sciences (NAS) recently published voluntary guidelines for human embryonic stem (hES) cell research. The NAS guidelines propose two levels of oversight. At the local level, research institutions are to create Embryonic Stem Cell Research Oversight (ESCRO) committees with a mandate to assess the scientific merit and ethical acceptability of hES cell research. At the national level, a new committee is to be created, not to review specific research proposals, but rather to periodically assess, and as needed revise, the NAS guidelines. In this article, we critically assess this proposal. In particular, we review the benefits and limitations of local research review. On this basis, we argue that local review is insufficient for hES cell research and that while there are obvious pragmatic and political reasons for the NAS to favor local research review, there are more compelling reasons for the NAS to have recommended national review of hES cell research proposals. 相似文献
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