模式识别课程中的统计学方法概述

模式识别是近年来迅速发展的一门学科,在工业、信息处理等领域有广泛应用。本文对模式识别、模式识别与统计学的关系进行了简单介绍,同时介绍了模式识别课程中两种基本的统计学方法：贝叶斯统计决策理论及概率密度估计理论。     

Multivariate geometric distributions

Families of multivariate geometric distributions with flexible correlations can be constructed by applying inverse sampling to a sequence of multinomial trials, and counting outcomes in possibly overlapping categories. Further multivariate families can be obtained by considering other stopping rules, with the possibility of different stopping roles for different counts, A simple characterisation is given for stopping rules which produce joint distributions with marginals having the same form as that of the number of trials. The inverse sampling approach provides a unified treatment of diverse results presented by earlier authors, including Goldberg (1934), Bates and Meyman (1952), Edwards and Gurland (1961), Hawkes (1972), Paulson and Uppulori (1972) and Griffiths and Milne (1987). It also provides a basis for investigating the range of possible correlations for a given set of marginal parameters. In the case of more than two joint geometric or negative binomial variables, a convenient matrix formulation is provided.     

Description and Propagation of Uncertainty in Input Parameters in Environmental Fate Models

Today, chemical risk and safety assessments rely heavily on the estimation of environmental fate by models. The key compound‐related properties in such models describe partitioning and reactivity. Uncertainty in determining these properties can be separated into random and systematic (incompleteness) components, requiring different types of representation. Here, we evaluate two approaches that are suitable to treat also systematic errors, fuzzy arithmetic, and probability bounds analysis. When a best estimate (mode) and a range can be computed for an input parameter, then it is possible to characterize the uncertainty with a triangular fuzzy number (possibility distribution) or a corresponding probability box bound by two uniform distributions. We use a five‐compartment Level I fugacity model and reported empirical data from the literature for three well‐known environmental pollutants (benzene, pyrene, and DDT) as illustrative cases for this evaluation. Propagation of uncertainty by discrete probability calculus or interval arithmetic can be done at a low computational cost and gives maximum flexibility in applying different approaches. Our evaluation suggests that the difference between fuzzy arithmetic and probability bounds analysis is small, at least for this specific case. The fuzzy arithmetic approach can, however, be regarded as less conservative than probability bounds analysis if the assumption of independence is removed. Both approaches are sensitive to repeated parameters that may inflate the uncertainty estimate. Uncertainty described by probability boxes was therefore also propagated through the model by Monte Carlo simulation to show how this problem can be avoided.     

On the use and evaluation of prospective scan methods for health-related surveillance

Summary.  We review some prospective scan-based methods that are used in health-related applications to detect increased rates of mortality or morbidity and to detect bioterrorism or active clusters of disease. We relate these methods to the use of the moving average chart in industrial applications. Issues that are related to the performance evaluation of spatiotemporal scan-based methods are discussed. In particular we clarify the definition of a recurrence interval and demonstrate that this measure does not reflect some important aspects of the statistical performance of scan-based, and other, surveillance methods. Some research needs in this area are given.     

The bivariate yule distribution and some of its properties

In this paper, a bivariate extension of the YULE distribution is defined and some of its structural properties are examined. It is shown in particular, that it can be obtained in the context of a bivariate STER model and as the only distribution with tail probabilities satisfying certain conditions     

A Markov Chain for calculating the durability of marriage

The usual Markov model of marriage permits informative experiments on the effect of alterations in the transition rules. It can tell, for example, what difference it would make to the durability of marriage if there was no divorce and the other transitions were as observed. This is in addition to the capacity of the usual model to find the effect of small changes in the transition rates.

Canadian data for 1970–1982 permit comparisons over time, and show among other things not only that married men live longer than single, but that the difference is increasing; the increase in the “marriage bonus”; over time also appears for women.     

基于小波变换的钻头实验信号降噪方法

在钻头破岩实验中存在钻头对岩石的周期性动载冲击, 同时受实验设备和环境等因素的影响, 在动态信号中存在着大量噪声, 无法获得准确的测试数据, 实验结果往往不能真实反映实验的特性和规律。基于小波变换的浮动阈值方法, 建立了一套用于钻头破岩实验测试信号噪声压制方法, 通过对实验和实测数据的处理和分析, 证明了方法有效性, 提高了实验数据的准确性和可靠性。     

Behavioral Impact of a Corporate Driving Policy

Abstract

Pizza deliverers at two stores received turn-signal policy statements with two paychecks in an AB1B2 multiple baseline design. At Store A turn-signal use rose from a baseline mean of 70% to 78% after the first policy statement and to 84% after the second policy statement. At Store B turn-signal use rose from a baseline mean of 46% to 51% after the first policy statement and to 59% after the second policy statement. Concurrent observations of safety-belt use showed decreases from 78% to 65% at Store A and 74% to 59% at Store B after the first policy statement.     

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