Alternative Bayes factors are families of methods used for hypothesis testing and model selection when sensitivity to priors
is a concern and also when prior information is weak or lacking. This paper deals with two related problems that arise in
the practical use of these model choice criteria: sample size determination and evaluation of discriminatory power. We propose
a pre-experimental approach to cope with both these issues. Specifically, extending the evidential approach of Royall (J Am Stat Assoc 95(451):760–780, 2000) and following De Santis (J Stat Plan Inference 124(1):121–144,
2004), we propose a criterion for sample size choice based on the predictive probability of observing decisive and correct
evidence. The basic idea is to select the minimal sample size that guarantees a sufficiently high pre-experimental probability
that an alternative Bayes factor provides strong evidence in favor of the true hypothesis. It is also argued that a predictive
analysis is a natural approach to the measurement of discriminatory power of alternative Bayes factors. The necessity of measuring
discrimination ability depends on the fact that alternative Bayes factors are, in general, less sensitive to prior specifications
than ordinary Bayes factors and that this gain in robustness corresponds to a reduced discriminative power. Finally, implementation
of the predictive approach with improper priors is discussed and possible strategies are proposed.
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Pontesei Dam is a major concrete dam built after World War II across the canyon of Maè Creek (Valle di Zoldo) in the Italian Eastern Alps. Just upstream from the dam, a gully discharges water from steep mountains. The only road serving the dam and the entire valley upstream of the dam runs along the mountainside and crosses the gully. In 1959, an exceptionally rainy season caused a flood, which destroyed the bridge. A temporary Bailey bridge was subsequently built by the army, but in 1990 it was decided to design a new bridge. The main challenges posed to the designer included building the new deck and the abutments underneath the Bailey bridge without disrupting traffic, hoisting the deck just to the bottom of the Bailey bridge, and finally substituting the new deck for the Bailey bridge in one day. Other problems included the instability of the rock mass at the abutments and the gravitative convergence of the two sides of the gully. This paper describes the design, construction, and testing of the bridge replacement and the bridge abutments. 相似文献
In this paper we introduce a new method to describe dynamical patterns of the real exchange rate co-movements time series and to analyze contagion in currency crisis. The method combines the tools of symbolic time series analysis with the nearest neighbor single linkage clustering algorithm. Data symbolization allows us obtaining a metric distance between two different time series that is used to construct an ultrametric distance. By analyzing the data of various countries, we derive a hierarchical organization, constructing minimal-spanning and hierarchical trees. From these trees we detect different clusters of countries according to their proximity. We show that this methodology permits us to construct a structural and dynamic topology that is useful to study interdependence and contagion effects among financial time series. 相似文献
Gaze-control enables people to control a computer by using eye-gaze to select items on screen. Gaze-control is a necessity
for people who have lost all motor control of their body and only have control over eye movements. In addition, gaze-control
can be the quickest and least tiring option for a far broader group of people with varying disabilities. This paper reports
findings from gaze-control user trials involving users from both groups: people who are totally paralyzed, as well as people
with a wide range of complex disabilities. The trials conducted involved four different centres supporting people with disabilities
in three different European countries. Several gaze-control systems were trialled by a large number of users with varying
needs and abilities. The perceived benefits of gaze-control are described, and recommendations for successful assessment and
implementation of gaze-control are provided. 相似文献
The capability of a compound or of a mixture of compounds to quench peroxyl radicals was measured by analyzing the kinetics
of the competition of a parallel reaction where peroxyl radicals bleach the carotenoid crocin. This kinetic approach, originally
described for the analysis of antioxidants reacting with hydroxyl radicals in water, was modified by both decreasing the polarity
of the solvent, thus allowing the analysis of lipophilic compounds, and by substituting a source of peroxyl radicals for the
hydroxyl radical generating system. Single compounds as well as complex mixtures were analyzed by kinetic data processing.
Overall antioxidant capacity, relative to that of α-tocopherol or of its soluble analog Trolox C, was calculated. As examples
of the use of this test, the antioxidant capacities of a crude rosemary extract, Maillard reaction products, and virgin olive
oils were measured. 相似文献
The forthcoming 5G technology aims to provide massive device connectivity and ultra-high capacity with reduced latency and costs. These features will be enabled by increasing the density of the base stations, using millimeter-wave (mmWave) bands, massive multiple-input multiple-output systems, and non-orthogonal multiple access techniques. The ability to support a large number of terminals in a small area is in fact a great challenge to guarantee massive access. In this context, this paper proposes a new receiver model for the uplink of 5G mmWave cellular networks. The receiver, called Iterative Decoding and Interference Cancellation (IDIC), is based on the Slotted Aloha (SA) protocol and exploits the capture effect alongside the successive IC process to resolve packet collisions. A 5G propagation scenario, modeled according to recent mmWave channel measurements, is used to compare IDIC with the widely adopted Contention Resolution Diversity SA (CRDSA) scheme to show the performance gain of IDIC, when elements of practical relevance, like imperfect cancellation and receive power diversity, are considered. The impact of packet and power diversity is also investigated to derive the preferable uplink random access strategy that maximizes the system throughput according to the offered channel load.
This work introduces metaheuristic approaches for designing resilient and cost‐effective multiprotocol label switching (MPLS) networks, a technology that is gaining prominent importance since most of the global data traffic is Internet traffic, and most internet protocol (IP) traffic within service provider backbones is being supported upon the IP/MPLS technology. Our approach is innovative because it integrates an overlay network design problem with the effective usage of traffic‐engineering features of this technology. Due to the resulting complexity and a high level of technological detail, we decided to use metaheuristics to find solutions to prospective scenarios for two real‐world applications. The best results were achieved using evolutionary algorithms and GRASP (Greedy Randomized Adaptive Search Procedure). The relative improvements for some of these scenarios are outstanding and reveal how using the protection mechanisms provided by newer technologies may advance efficiency standards more than legacy protection schemas. 相似文献
The single-objective optimization of structures, whose parameters are assigned as fuzzy numbers or fuzzy relations, is presented in this paper as a particular case of the random set theory and evidence theory approach to uncertainty. Some basic concepts concerning these theories are reviewed and the relationships among interval analysis, convex modeling, possibility theory and probability theory are pointed out. In this context a frequentistic view of fuzzy sets makes sense and it is possible to calculate bounds on the probability that the solution satisfies the constraints. Some special but useful cases illustrate in detail the meaning of the approach proposed and its links with a recent formulation conceived within the context of convex modeling. Some theorems allow a very efficient computational procedure to be set up in many real design situations. Two numerical examples illustrate the model presented. 相似文献