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71.
Point processes are the stochastic models most suitable for describing physical phenomena that appear at irregularly spaced
times, such as the earthquakes. These processes are uniquely characterized by their conditional intensity, that is, by the
probability that an event will occur in the infinitesimal interval (t, t+Δt), given the history of the process up tot. The seismic phenomenon displays different behaviours on different time and size scales; in particular, the occurrence of
destructive shocks over some centuries in a seismogenic region may be explained by the elastic rebound theory. This theory
has inspired the so-called stress release models: their conditional intensity translates the idea that an earthquake produces
a sudden decrease in the amount of strain accumulated gradually over time along a fault, and the subsequent event occurs when
the stress exceeds the strength of the medium. This study has a double objective: the formulation of these models in the Bayesian
framework, and the assignment to each event of a mark, that is its magnitude, modelled through a distribution that depends
at timet on the stress level accumulated up to that instant. The resulting parameter space is constrained and dependent on the data,
complicating Bayesian computation and analysis. We have resorted to Monte Carlo methods to solve these problems. 相似文献
72.
Michael S. Rendall Ryan Admiraal Alessandra DeRose Paola DiGiulio Mark S. Handcock Filomena Racioppi 《Statistical Methods and Applications》2008,17(4):519-539
In non-experimental research, data on the same population process may be collected simultaneously by more than one instrument.
For example, in the present application, two sample surveys and a population birth registration system all collect observations
on first births by age and year, while the two surveys additionally collect information on women’s education. To make maximum
use of the three data sources, the survey data are pooled and the population data introduced as constraints in a logistic
regression equation. Reductions in standard errors about the age and birth-cohort parameters of the regression equation in
the order of three-quarters are obtained by introducing the population data as constraints. A halving of the standard errors
about the education parameters is achieved by pooling observations from the larger survey dataset with those from the smaller
survey. The percentage reduction in the standard errors through imposing population constraints is independent of the total
survey sample size. 相似文献
73.
74.
75.
Banks winners in tournaments are difficult to recognize 总被引:1,自引:0,他引:1
Gerhard J. Woeginger 《Social Choice and Welfare》2003,20(3):523-528
Given a tournament T, a Banks winner of T is the top vertex of any maximal (with respect to inclusion) transitive subtournament of T. In this technical note, we show that the problem of deciding whether some fixed vertex v is a Banks winner for T is NP-complete.
Received: 22 February 2002/Accepted: 20 June 2002
Supported by the START program Y43-MAT of the Austrian Ministry of Science.
I would like to thank two thank the referees for a careful reading of the paper, for helpful remarks, and for many suggestions
how to improve the presentation. 相似文献
76.
Gayane Novikova 《Transition Studies Review》2004,11(3):213-223
The collapse of the USSR was accompanied by transformation of the South Caucasian latent ethnopolitical conflicts into local wars. Today the situation in the area of the conflicts is “neither war, nor peace”. Three unresolved conflicts of the South Caucasus can be considered as one of the most serious obstacles for establishing a regional security system.The article gives the general characteristics of these conflicts, the trends of their development, taking into account the time factor, and analyzes the behavioral models of the main players – de jure recognized and unrecognized de facto states of the South Caucasus. The basic objective of the main players should be to keep the situation on a level preventing the resumption of the armed conflicts. The attempts of forced resolution of the conflicts are fraught with destabilization of the situation not only in the area of any of these conflicts but in the whole region. 相似文献
77.
D. R. Cox Man Yu Wong 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2004,66(2):395-400
Summary. Given a large number of test statistics, a small proportion of which represent departures from the relevant null hypothesis, a simple rule is given for choosing those statistics that are indicative of departure. It is based on fitting by moments a mixture model to the set of test statistics and then deriving an estimated likelihood ratio. Simulation suggests that the procedure has good properties when the departure from an overall null hypothesis is not too small. 相似文献
78.
Lu Lin 《Statistical Papers》2004,45(4):529-544
The quasi-score function, as defined by Wedderburn (1974) and McCullagh (1983) and so on, is a linear function of observations.
The generalized quasi-score function introduced in this paper is a linear function of some unbiased basis functions, where
the unbiased basis functions may be some linear functions of the observations or not, and can be easily constructed by the
meaning of the parameters such as mean and median and so on. The generalized quasi-likelihood estimate obtained by such a
generalized quasi-score function is consistent and has an asymptotically normal distribution. As a result, the optimum generalized
quasi-score is obtained and a method to construct the optimum unbiased basis function is introduced. In order to construct
the potential function, a conservative generalized estimating function is defined. By conservative, a potential function for
the projected score has many properties of a log-likelihood function. Finally, some examples are given to illustrate the theoretical
results.
This paper is supported by NNSF project (10371059) of China and Youth Teacher Foundation of Nankai University. 相似文献
79.
Starting with its early twentieth century origins, the development of Labor Economics is traced to the present. We describe
an intellectual revolution in which an earlier tra-dition that focused primarily on the institution of the labor union has
been replaced by a perspective that emphasizes the various roles played by labor markets in an eco-nomic system. That earlier
tradition contained very significant ideological elements, whereas its successor deals much more with the world of ideas.
In the course of the debate, which still continues, ideas triumphed over ideology and created modern Labor Economics. 相似文献
80.