The beta-binomial convolution model for 2×2 tables with missing cell counts

This paper considers the beta-binomial convolution model for the analysis of 2×2 tables with missing cell counts. We discuss maximum-likelihood (ML) parameter estimation using the expectation–maximization algorithm and study information loss relative to complete data estimators. We also examine bias of the ML estimators of the beta-binomial convolution. The results are illustrated by two example applications.     

Comparing environmental impacts of regional and national-scale food supply chains: A case study of processed tomatoes

This study uses life cycle assessment methodology to quantify the energy use, greenhouse gas (GHG) emissions, and water use of processed tomato products grown, processed, and consumed within the Great Lakes region of the United States, and tomato products produced in California and then shipped to the Great Lakes region for consumption. The purpose is to assess the potential for regional food systems to reduce selected environmental impacts, particularly the energy and GHG footprints, of consumer-ready, processed food products, when compared to national-scale food systems in which consumer products are shipped long distances. The study also examines the role of different types of food processing in influencing life cycle energy use, water use, and emissions.Our results indicate that California-produced conventional and organic tomato paste and canned diced tomatoes are almost equivalent in energy use and GHG emissions to regionally produced and consumed products, but use of developed water resources is significantly higher for California-grown products. California tomato production benefits from higher per hectare yields and soil amendments with lower carbon dioxide emissions. These efficiencies substantially offset the added energy use and GHG emissions associated with long-distance shipment of products to the Great Lakes region, as long as shipments are made by rail rather than by truck. Paste, the more processed and concentrated product evaluated, amplifies any environmental advantages or disadvantages accrued in the field production stage, due to its raw tomato to finished product ratio of 6:1, suggesting that comparative regional advantage can play a role in lowering life cycle environmental impacts of highly condensed foods shipped long distances.     

Inequalities relating maximal moments to other measures of dispersion

Let X , X ₁, ..., X_k be i.i.d. random variables, and for k ∈ N let D_k ( X ) = E ( X ₁ V ... V X _{k +1}) − EX be the k th centralized maximal moment. A sharp lower bound is given for D ₁( X ) in terms of the Lévy concentration Q_l ( X ) = sup _{x ∈ R} P ( X ∈[ x , x + l ]). This inequality, which is analogous to P. Levy's concentration-variance inequality, illustrates the fact that maximal moments are a gauge of how much spread out the underlying distribution is. It is also shown that the centralized maximal moments are increased under convolution.     

Explanators of Local Government Distress

This article develops a statistical model to explain sources of distress in local government. Whereas ‘financial distress’ in the private sector has been equated with a failure to meet financial commitments, here ‘distress’ is interpreted as an inability to maintain pre-existing levels of services to the community. Since the late 1990s local councils in an Australian state (New South Wales) have been required to estimate the cost of restoring infrastructure assets to a satisfactory condition (a requirement which predates that form of reporting on infrastructure condition introduced as an option in U.S. GASB 34). Information regarding the cost of restoring infrastructure is used in this study as a proxy for levels of distress (in contrast to the binary classification that characterizes much of prior private sector financial distress research). Data regarding service levels for a sample of 161 councils for 2001 and 2002 were used and a multiple regression model was estimated and interpreted. The main findings were that the degree of distress in local councils is positively associated with the size of the population they serve and the size and composition of their revenues. Road maintenance costs featured prominently in results, as higher road program costs were associated with higher levels of distress (particularly when interacted with other variables). However, the revenue generating capacity of councils had the strongest statistical impact on local government distress. Councils with lower percentages of rates revenue to total revenue and lower ordinary revenue levels to total assets were typically identified as more distressed. However, no systematic evidence was found that rural councils have higher distress levels than urban councils (i.e., both rural and urban councils serving larger populations were relatively more distressed than councils serving smaller populations). It is suggested that the model (or modifications thereof) may serve as an early warning system for those monitoring the circumstances and performance of local governments.     

Simulated Likelihood Estimation of the Normal-Gamma Stochastic Frontier Function

The normal-gamma stochastic frontier model was proposed in Greene (1990) and Beckers and Hammond (1987) as an extension of the normal-exponential proposed in the original derivations of the stochastic frontier by Aigner, Lovell and Schmidt (1977). The normal-gamma model has the virtue of providing a richer and more flexible parameterization of the inefficiency distribution in the stochastic frontier model than either of the canonical forms, normal-half normal and normal-exponential. However, several attempts to operationalize the normal-gamma model have met with very limited success, as the log likelihood is possesed of a significant degree of complexity. This note will propose an alternative approach to estimation of this model based on the method of maximum simulated likelihood estimation as opposed to the received attempts which have approached the problem by direct maximization.     

平方根升余弦滚降FIR数字滤波器的设计

本文采用本地查找算法，根据不同的误差准则设计了一系列平方根升余弦滚降FIR滤波器，并且在基带传输系统中对FIR滤波器进行了性能仿真，得出了在对称度准则下设计的FIR滤波器具有较好的性能的结论。     

The analysis of proportions in agricultural experiments by a generalized linear mixed model

This paper is concerned with the statistical analysis of proportions involving extra-binomial variation. Extra-binomial variation is inherent to experimental situations where experimental units are subject to some source of variation, e.g. biological or environmental variation. A generalized linear model for proportions does not account for random variation between experimental units. In this paper an extended version of the generalized linear model is discussed with special reference to experiments in agricultural research. In this model it is assumed that both treatment effects and random contributions of plots are part of the linear predictor. The methods are applied to results from two agricultural experiments.     

The density of the parameter estimators when the observations are distributed exponentially

We present the probability density of parameter estimators whenN independent variables are observed, each of them distributed according to the exponential low (with some parameters to be estimated). The numberN is supposed to be small. Typically, such an experimental situation arises in problems of software reliability, another case is a small sample in the GLIM modeling. The considered estimator is defined by the maximum of the posterior probability density; it is equal to the maximum likelihood estimator when the prior is uniform. The exact density is obtained, and its approximation is discussed in accordance with some information-geometric considerations. The main body of the paper has been prepared during the author’s visit in LMC/IMAG Grenoble, France, on the invitation of Université Joseph Fourier in January 1994.     

Nonparametric maximum likelihood estimation in a non locally compact setting

Maximum likelihood estimation is considered in the context of infinite dimensional parameter spaces. It is shown that in some locally convex parameter spaces sequential compactness of the bounded sets ensures the existence of minimizers of objective functions and the consistency of maximum likelihood estimators in an appropriate topology. The theory is applied to revisit some classical problems of nonparametric maximum likelihood estimation, to study location parameters in Banach spaces, and finally to obtain Varadarajan’s theorem on the convergence of empirical measures in the form of a consistency result for a sequence of maximum likelihood estimators. Several parameter spaces sharing the crucial compactness property are identified. This research was supported by grants from the National Sciences and Engineering Research Council of Canada and the Fonds FCAR de la Province de Québec.     

Identifying, estimating and testing restricted cointegrated systems: An overview

The notion of cointegration has led to a renewed interest in the identification and estimation of structural relations among economic time series. This paper reviews the different approaches that have been put forward in the literature for identifying cointegrating relationships and imposing (possibly over-identifying) restrictions on them. Next, various algorithms to obtain (approximate) maximum likelihood estimates and likelihood ratio statistics are reviewed, with an emphasis on so-called switching algorithms. The implementation of these algorithms is discussed and illustrated using an empirical example.