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1.
The optimality of designs obtained by adding p runs to an orthogonal array is studied for experiments involving m factors each at s levels. The optimality criterion used here, is the Type 1 criterion due to Cheng (1978) which is an extension of Kiefer (1975)
universal optimality criterion. Unlike what happens with orthogonal array plus one run designs, the behavior of designs obtained
via augmentation of an orthogonal array by p runs depends on the particular runs added. 相似文献
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The process capability index C
pm
, which considers the process variance and departure of the process mean from the target value, is important in the manufacturing
industry to measure process potential and performance. This paper extends its applications to calculate the process capability
index [(C)\tilde]pm{\tilde {C}_{pm} } of fuzzy numbers. In this paper, the α-cuts of fuzzy observations are first derived based on various values of α. The membership function of fuzzy process capability index [(C)\tilde]pm{\tilde {C}_{pm} } is then constructed based on the α-cuts of fuzzy observations. An example is presented to demonstrate how the fuzzy process capability index [(C)\tilde]pm{\tilde {C}_{pm} } is interpreted. When the quality characteristic cannot be precisely determined, the proposed method provides the most possible
value and spread of fuzzy process capability index [(C)\tilde]pm{\tilde {C}_{pm} }. With crisp data, the proposed method reduces to the classical method of process capability index C
pm
. 相似文献
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Mike Jacroux 《Metrika》2007,65(2):235-242
Two level regular fractional factorial designs are often used in industry as screening designs to help identify early on in
an experimental process those experimental or system variables which have significant effects on the process being studied.
In a recent paper, Li and Lin (2003) suggested a strategy for constructing optimal follow up designs using the well known
foldover technique and the minimum aberration criterion. In this paper, we extend the results of Li and Lin (2003) by giving
an alternate technique for constructing optimal follow up designs using the foldover technique in conjunction with the maximal
rank–minimum aberration criterion suggested in Jacroux (2003). 相似文献
4.
Top-k-lists are introduced as sequences of k-dimensional random vectors with ordered components being k largest observations from a sequence of independent identically distributed random variables. Such lists changing in time are natural stochastic models of ranking tables which appear in many situations in real life, when one wants to keep a track of several best results in a given field. Here we study basic properties of top-k-lists as joint distributions, conditional structures, representations, driving examples of top-k-lists from exponential and uniform distributions, asymptotics and a relation to generalized order statistics. 相似文献
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Paul VANDENBERG 《Revista Internacional del Trabajo》2010,129(1):33-63
Incitados por la competencia mundial, muchos países están adaptando la reglamentación laboral al principio de la «flexiseguridad>>, que da a las empresas más flexibilidad para contratar y despedir a los trabajadores, al tiempo que ampara a éstos cuando deben pasar de un empleo a otro. El presente estudio de seis países asiáticos indica que China y República de Corea han promulgado reformas de este género; Singapur y Malasia han implantado algunos elementos de «flexiseguridad>>, pero no un seguro de desempleo, y la India y Sri Lanka han hecho pocas reformas y mantienen un modelo anticuado en el que la protección depende de la empresa. Para prestar apoyo a los trabajadores del sector informal, China, India y Sri Lanka se valen de obras públicas y de programas de fomento del trabajo por cuenta propia y de formación profesional. 相似文献
6.
It is well-known that the naive bootstrap yields inconsistent inference in the context of data envelopment analysis (DEA)
or free disposal hull (FDH) estimators in nonparametric frontier models. For inference about efficiency of a single, fixed
point, drawing bootstrap pseudo-samples of size m < n provides consistent inference, although coverages are quite sensitive to the choice of subsample size m. We provide a probabilistic framework in which these methods are shown to valid for statistics comprised of functions of
DEA or FDH estimators. We examine a simple, data-based rule for selecting m suggested by Politis et al. (Stat Sin 11:1105–1124, 2001), and provide Monte Carlo evidence on the size and power of our tests. Our methods (i) allow for heterogeneity in the inefficiency
process, and unlike previous methods, (ii) do not require multivariate kernel smoothing, and (iii) avoid the need for solutions
of intermediate linear programs. 相似文献
7.
This paper examines the wide-spread practice where data envelopment analysis (DEA) efficiency estimates are regressed on some
environmental variables in a second-stage analysis. In the literature, only two statistical models have been proposed in which
second-stage regressions are well-defined and meaningful. In the model considered by Simar and Wilson (J Prod Anal 13:49–78,
2007), truncated regression provides consistent estimation in the second stage, where as in the model proposed by Banker and Natarajan
(Oper Res 56: 48–58, 2008a), ordinary least squares (OLS) provides consistent estimation. This paper examines, compares, and contrasts the very different
assumptions underlying these two models, and makes clear that second-stage OLS estimation is consistent only under very peculiar
and unusual assumptions on the data-generating process that limit its applicability. In addition, we show that in either case,
bootstrap methods provide the only feasible means for inference in the second stage. We also comment on ad hoc specifications
of second-stage regression equations that ignore the part of the data-generating process that yields data used to obtain the
initial DEA estimates. 相似文献
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In this paper, Bayesian estimation of log odds ratios over R × C and 2 × 2 × K contingency tables is considered, which is practically reasonable in the presence of prior information. Likelihood functions for log odds ratios are derived for each table structure. A prior specification strategy is proposed. Posterior inferences are drawn using Gibbs sampling and Metropolis–Hastings algorithm. Two numerical examples are given to illustrate the matters argued. 相似文献
10.
This paper defines a set of indicators for distinguishing housing affordability problems resulting from high rents from those chiefly arising from low income. In place of the common ratio of rent to income, it uses a residual income indicator with indicators of over-consumption and over-paying for housing services. The indicators are computed for a sample of renter households in Switzerland, one of the countries with the greatest rental share. They help define more precisely who needs general income assistance and who needs specific housing aid (only one fourth of the former). 相似文献
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Carl J. Schwarz 《Revue internationale de statistique》2007,75(3):348-354
The very soul of statistics are data, but few students actually collect data as part of their statistical journey. The impediments to real data collection exercises are very real—they are logistically difficult to set up, expensive, and may not work because of extraneous events outside the control of the instructor. Computer‐aided laboratories are a way to bring many of the benefits of actual data collection to students at a fraction of the cost and can be easily controlled by the instructor. There are many computer‐aided modules available—indeed a search on Google gave over 1 million hits. Some modules are good but many are mediocre. What separates the gems from the trash? 相似文献
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