bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Simple Derivation of Deletion Diagnostic Results for the General Linear Model with Correlated Errors
Authors: Haslett John 
Published: March 2003

Summary
A general, simple and intuitive derivation is provided for diagnostics associated with the deletion of arbitrary subsets for the linear model with general covariance structure. These are seen to be most simply expressed, even for the well-studied case of independent and identically distributed data, in terms of a residual known variously as the conditional residual, the deletion prediction residual and the cross-validation residual. Particularly simple specializations arise when the subsets are of size 1 and of size 2, but the method is easy to apply for all subsets and to conditional deletions.
Probabilistic Principal Component Analysis
Authors: Tipping Michael E. , Bishop Christopher M. 
Published: March 2003

Summary
Principal component analysis (PCA) is a ubiquitous technique for data analysis and processing, but one which is not based on a probability model. We demonstrate how the principal axes of a set of observed data vectors may be determined through maximum likelihood estimation of parameters in a latent variable model that is closely related to factor analysis. We consider the properties of the associated likelihood function, giving an EM algorithm for estimating the principal subspace iteratively, and discuss, with illustrative examples, the advantages conveyed by this probabilistic approach to PCA.
Goodness of Fit of Generalized Linear Models to Sparse Data
Authors: Paul Sudhir R. , Deng Dianliang 
Published: March 2003

Summary
We derive approximations to the first three moments of the conditional distribution of the deviance statistic, for testing the goodness of fit of generalized linear models with non-canonical links, by using an estimating equations approach, for data that are extensive but sparse. A supplementary estimating equation is proposed from which the modified deviance statistic is obtained. An application of a modified deviance statistic is shown to binomial and Poisson data. We also conduct a performance study of the modified Pearson statistic derived by Farrington and the modified deviance statistic derived in this paper, in terms of size and power, through a small scale simulation experiment. Both statistics are shown to perform well in terms of size. The deviance statistic, however, shows an advantage of power. Two examples are given.
Robust Estimation for Finite Populations Based on a Working Model
Authors: Kuk Anthony Y. C. , Welsh A. H. 
Published: March 2003

Summary
A common scenario in finite population inference is that it is possible to find a working superpopulation model which explains the main features of the population but which may not capture all the fine details. In addition, there are often outliers in the population which do not follow the assumed superpopulation model. In situations like these, it is still advantageous to make use of the working model to estimate finite population quantities, provided that we do it in a robust manner. The approach that we suggest is first to fit the working model to the sample and then to fine-tune for departures from the model assumed by estimating the conditional distribution of the residuals as a function of the auxiliary variable. This is a more direct approach to handling outliers and model misspecification than the Huber approach that is currently being used. Two simple methods, stratification and nearest neighbour smoothing, are used to estimate the conditional distributions of the residuals, which result in two modifications to the standard model-based estimator of the population distribution function. The estimators suggested perform very well in simulation studies involving two types of model departure and have small variances due to their model-based construction as well as acceptable bias. The potential advantage of the proposed robustified model-based approach over direct nonparametric regression is also demonstrated.
A Basis Function Approach to Position Estimation Using Microwave Arrays
Authors: Webb Andrew R. , Garner Philip N. 
Published: March 2003

SUMMARY
We consider the problem of estimating the bearing of a remote object given measurements on a particular type of non-scanning radar, namely a focal-plane array. Such a system focuses incoming radiation through a lens onto an array of detectors. The problem is to estimate the angular position of the radiation source given measurements on the array of detectors and knowledge of the properties of the lens. The training data are essentially noiseless, and an estimator is derived for noisy test conditions. An approach based on kernel basis functions is developed. The estimate of the basis function weights is achieved through a regularization or roughness penalty approach. Choosing the regularization parameter to be proportional to the inverse of the input signal-to-noise ratio leads to a minimum prediction error. Experimental results for a 12-element detector array support the theoretical predictions.
Simulation and Extremal Analysis of Hurricane Events
Authors: Casson Edward , Coles Stuart 
Published: March 2003

SUMMARY
In regions affected by tropical storms the damage caused by hurricane winds can be catastrophic. Consequently, accurate estimates of hurricane activity in such regions are vital. Unfortunately, the severity of events means that wind speed data are scarce and unreliable, even by standards which are usual for extreme value analysis. In contrast, records of atmospheric pressures are more complete. This suggests a two-stage approach: the development of a model describing spatiotemporal patterns of wind field behaviour for hurricane events; then the simulation of such events, using meteorological climate models, to obtain a realization of associated wind speeds whose extremal characteristics are summarized. This is not a new idea, but we apply careful statistical modelling for each aspect of the model development and simulation, taking the Gulf and Atlantic coastlines of the USA as our study area. Moreover, we address for the first time the issue of spatial dependence in extremes of hurricane events, which we find to have substantial implications for regional risk assessments.
Using a Box–Cox Transformation in the Analysis of Longitudinal Data with Incomplete Responses
Authors: Lipsitz Stuart R. , Ibrahim Joseph , Molenberghs Geert 
Published: March 2003

SUMMARY
We analyse longitudinal data on CD4 cell counts from patients who participated in clinical trials that compared two therapeutic treatments: zidovudine and didanosine. The investigators were interested in modelling the CD4 cell count as a function of treatment, age at base-line and disease stage at base-line. Serious concerns can be raised about the normality assumption of CD4 cell counts that is implicit in many methods and therefore an analysis may have to start with a transformation. Instead of assuming that we know the transformation (e.g. logarithmic) that makes the outcome normal and linearly related to the covariates, we estimate the transformation, by using maximum likelihood, within the Box–Cox family. There has been considerable work on the Box–Cox transformation for univariate regression models. Here, we discuss the Box–Cox transformation for longitudinal regression models when the outcome can be missing over time, and we also implement a maximization method for the likelihood, assumming that the missing data are missing at random.
Bayesian Inference for Rare Errors in Populations with Unequal Unit Sizes
Authors: Laws David J. , O’Hagan Anthony 
Published: March 2003

SUMMARY
We describe a Bayesian model for a scenario in which the population of errors contains many 0s and there is a known covariate. This kind of structure typically occurs in auditing, and we use auditing as the driving application of the method. Our model is based on a categorization of the error population together with a Bayesian nonparametric method of modelling errors within some of the categories. Inference is through simulation. We conclude with an example based on a data set provided by the UK’s National Audit Office.
Estimating the Transmission Probability of Human Immunodeficiency Virus in Injecting Drug Users in Thailand
Authors: Hudgens Michael G. , Longini Ira. M. , Halloran M. Elizabeth , Choopanya Kachit , Vanichseni Suphak , Kitayaporn Dwip , Mastro Timothy D. , Mock Philip A. 
Published: March 2003

SUMMARY
We estimate the transmission probability for the human immunodeficiency virus from seroconversion data of a cohort of injecting drug users (IDUs) in Thailand. The transmission probability model developed accounts for interval censoring and incorporates each IDU’s reported frequency of needle sharing and injecting acts. Using maximum likelihood methods, the per needle sharing act transmission probability estimate between infectious and susceptible IDUs is 0.008. The effects of covariates, disease dynamics, mismeasured exposure information and the uncertainty of the disease prevalence on the transmission probability estimate are considered.
Incorporation of Historical Controls Using Semiparametric Mixed Models
Authors: Parise Helen , Wand M. P. , Ruppert David , Ryan Louise 
Published: March 2003

SUMMARY
The analysis of animal carcinogenicity data is complicated by various statistical issues. A topic of recent debate is how to control for the effect of the animal’s body weight on the outcome of interest, the onset of tumours. We propose a method which incorporates historical information from the control animals in previously conducted experiments. We allow non-linearity in the effects of body weight by modelling the relationship nonparametrically through a penalized spline. A simple extension of the penalized spline model allows the relationship between weight and the onset of tumour to vary from one experiment to another.
Analysis of Repeated Failures or Durations, with Application to Shunt Failures for Patients with Paediatric Hydrocephalus
Authors: Lawless J. F. , Wigg M. B. , Tuli S. , Drake J. , Lamberti-Pasculli M. 
Published: March 2003

SUMMARY
We consider studies involving the repeated occurrence of certain events, in which the emphasis is on the gaps or times between events. Interesting methodological issues arise in such situations, including the validity of semiparametric methods for multiplicative hazard-based models and the possibilities for marginal analysis of successive gap times. We discuss these and other points in conjunction with an examination of observational data on repeated shunt failures for a population of children with hydrocephalus.
Does the Public Sector Lead the Wage Evolution in the French Economy?
Authors: Redor Dominique 
Published: March 2003

Has the wage policy of the State in the French public sector (government services and State owned enterprises) had a leading effect on wages in the private sector up until the early 1980s?This paper firstly aims at verifying the existence and analysing the causes of this leading effect. The second aim is to estimate the scope of the changes which took place from the early 1980s. It shows that the wage policy of the State did influence disinflation in the 1980s and early 1990s. Indeed, it not only slowed down the growth of wages in the public sector but, by this means, it also influenced indireclty the growth of wages in the private sector.
Consumption and Wealth: An International Comparison
Authors: Sefton J. A. , In’t Veld J. W. 
Published: March 2003

This paper derives the discrete‐time counterpart of Blanchard’s overlapping generations model of consumer expenditure. The model is combined with two different models of liquidity‐constrained consumers; in the first the percentage of income accruing to such consumers is constant; in the second it is allowed to decrease over time. These models are estimated for five countries over the period 1967–92, and pass all standard specifications as well as some alternative non‐parametric tests.Our estimates suggest that in Canada and the USA the number of liquidity‐constrained consumers decreased substantially in the late 1970s and early 1980s. In Germany and the UK these changes occurred later and were less pronounced.
A Solution to the Paradox of Analysis
Authors: Kuczynski John‐Michael 
Published: March 2003

This essay attempts to solve the so‐called paradox of analysis: if one is to have any questions about x, one must know x; but if one knows x, one has no questions about x. The obvious solution is this: one can inquire into x if one knows some, but not all, of x's parts. But this solution is erroneous. Let x′ be those parts of x with which one is acquainted, and let S be the percipient in question. As with x, either S knows x′, in which case he has no questions about it; or S does not know x′, in which case he has no questions about it.My solution is this. Perception and cognition give us, not the thing‐in‐itself, but a certain analogue of the thing‐in‐itself. To inquire into x, it is necessary to know not x, but only some analogue of x; and to learn more about x is to become acquainted with increasingly precise analogues of x.
The Struggle over Employee Benefits: The Role of Labor in Influencing Modern Health Policy
Authors: Rosner David , Markowitz Gerald 
Published: March 2003

Health care policy has often been described as the work of political actors seeking to benefit the larger community or a particular group of individuals. In 20th‐century America, those actors worked in a historical context shaped by demographic and political pressures created during a period of rapid industrial change. Whereas scholars have placed the emergence of European social welfare in such a larger frame, their analysis of movements for health insurance in the United States has largely ignored the need for a frame. If anything, their studies have focused on the lack of a radical political working‐class movement in this country as an explanation for the absence of national or compulsory health insurance. Indeed, this absence has dominated analyses of the failure of health policy reform in this country, which generally ignore even these passing historical allusions to the role of class in shaping health policy. Explanations of why health care reform failed during the Clinton administration cited the lack of coverage for millions of Americans but rarely alluded to the active role of labor or other working‐class groups in shaping the existing health care system.After organized labor failed to institute national health insurance in the mid‐twentieth century, its influence on health care policy diminished even further. This article proposes an alternative interpretation of the development of health care policy in the United States, by examining the association of health policy with the relationships between employers and employees. The social welfare and health insurance systems that resulted were a direct outcome of the pressures brought by organized and unorganized labor movements. The greater dependency created by industrial and demographic changes, conflicts between labor and capital over the political meaning of disease and accidents, and attempts by the political system to mitigate the impending social crisis all helped determine new health policy options.
2. More Conformity or More Data?
Authors: Crippen Dan 
Published: March 2003

Sherry Glied and her colleagues have done an excellent job of laying out some of the modeling approaches and techniques, underlying assumptions, and results of various studies of health insurance coverage. Their observations about the lack of comparability of results are especially helpful.Their proposed solution of a reference case may be premature, however, and, if widely adopted, stultifying. The truth is that health care research even beyond assumptions remains formative. That is, the results are scattered, not so much because of the investigators’ caprice, but because the models, and particularly the data, do not yet lend themselves to clear and consistent conclusions.This does not mean that the typology of assumptions, for example, is not useful; quite the contrary. But it does mean that when regression results can explain only 10 to 20 percent of the variance, it may be counterproductive to attempt to impose a reference case.
6. Response to Comments
Authors: Glied Sherry , Remler Dahlia K. , Zivin Joshua Graff 
Published: March 2003

We appreciate the interest and criticisms of our commentators. Our effort to encourage modelers to engage with one another and with the consumers of modeling results appears to have had an immediate benefit, and we hope this is the beginning of a continuing dialogue.We recognize, as Crippen, Fishman, and Nexon noted, that the Congressional Budget Office (CBO) operates under different constraints than do private modelers. While we do not specifically address how forthcoming the CBO should be about its model, we believe that greater transparency in the private modeling community regarding assumptions would help the CBO refine its model and respond to legislative requests. It would also, as Fishman and Nexon suggested, help the legislative staffers who work with the CBO.Pauly points out a problem, the choice of an appropriate price variable, that we did not include in our sample of issues. Undoubtedly others—as well as new issues—will surface as policies evolve. As Fishman observed, there is ample room for improving models.
The Effect of Import Substitution Policy on Manufacturing Industries in Iraq
Authors: Zaidan T. M. 
Published: March 2003

This paper examines the possibilities for import substitution in manufacturing industries in Iraq. To do this, it devises three measures of import substitution and applies them to 14 defined industries for the period 1978–88; this period, in turn, is divided into sub‐periods, 1978–82 and 1982–88. The paper also evaluates the effects of substitution on patterns of growth in these industries. The results range from high to low levels of substitution, as well as negative ones. The paper, in particular, highlights the agricultural sector as needing to be subsidised and encouraged to increase production.Generally, the analysis suggests that, in the period under review, the Iraqi economy succeeded in the first state of import substitution, namely the manufacture of consumer goods, and displayed good potential in the second, namely the manufacture of intermediate and capital goods. It concludes by saying that international pressures played an important role in encouraging substitution in 1978–88.
The Price of Crude Oil
Authors: Bakhtiari A.M. Samsam 
Published: March 2003

The price of crude oil is among the most important prices quoted daily across the world — which is not surprising, since crude oil is the most widely used source of energy worldwide, as well as being a unique commodity.When petroleum burst onto the world stage in 1859, its price first went through some initial gyrations (1860–70), before settling in the $1.00–2.00 per barrel range (barring a few exceptions) for a full century.Then, the price underwent two ‘shocks’ (1973 and 1980), followed by the ‘counter‐shock’ of 1986. Thereafter, the price entered the relative stability of the $15–20/b concensus, where it lingered until recently.Some day, there is bound to be a fresh paradigm of ‘insufficient oil reserves’, thus ushering in a new era for oil prices. Taking into consideration available data on reserves and expert analysis, it would seem that that day may be years rather than decades away.
Electricity Demand by the Commercial Sector in Kuwait: An Econometric Analysis
Authors: Eltony M. Nagy , Hajeeh Mohammad 
Published: March 2003

This paper models and estimates electricity demand by the Kuwaiti commercial sector, using an error correction model. It also simulates the estimated model under three scenarios and presents an analysis of the results.The empirical results indicate that short‐ and long‐run electricity consumption and the level of economic activity are interrelated. The forecasts show that electricity consumption varies directly with economic growth. They also suggest that an increase of 100 per cent in nominal electricity prices will lead to a reduction in commercial sector electricity demand of 45 per cent by the year 2010. The simulation of the model under the different scenarios demonstrates that the potential for energy conservation exists in the commercial sector.
The Oil and Gas Links Between Central Asia and China: a Geopolitical Perspective
Authors: Xu Xiaojie 
Published: March 2003

This paper is dedicated to a better understanding of the oil and gas links between Central Asia and China and the sequential implications. The author’s message is threefold.1. China’s growing economic momentum, coupled with its energy constraints, has led the country to search for overseas resources. Considering the fact that Central Asia enjoys prolific hydrocarbon resources, while China has huge energy demands, there is no doubt about the economic and geopolitical importance of Central Asian resources to China. What China needs to do now is to build a bridge to link these resources. The key rationale behind this is a regional energy linkage, which constitutes a new visionary way of handling input into China.2. Considering the costs of the transportation infrastructure inside China and the comparison between the replacement costs of foreign and domestic oil, it makes sense for China to move westwards to maximise the benefits from Central Asia and other neighbouring regions. At the same time, China has to bear the huge cost of overseas expansion and high risk, both economically and geopolitically.3. China cannot ignore the new “Great Game” played in Central Asia and the Caucasus region. All the major powers involved so far have their varying motivations and advantages to reap from their influence on the landlocked region. China, advantageously positioned on the border of Central Asia, sees an opportunity to broaden its geo‐economic role in the region and beyond, so as to become a more important geopolitical force. At the turn of the century, China will give higher priority to market penetration and aggressive diplomacy. Further alliances and geopolitical goals in Central Asia, the Middle East and Russia will be explored. However, the benefits to China will depend on the effective management of uncertainties and the status of its geopolitical strength.
The Development and Acquisition of Oil Licences and Leases in Nigeria
Authors: Atsegbua Lawrence 
Published: March 2003

This paper examines the development of the modes of acquisition of oil licences and leases in the Nigerian oil industry from 1914 to the present day.It begins with an historical overview, highlighting, among other things, the dominance of Shell‐BP up to independence in 1960. The next two sections focus on the acquisition of oil rights before and after the landmark Petroleum Act of 1969, followed by a comparison of the pre‐ and post‐1969 frameworks.Finally, the paper looks at the present system of production‐sharing contracts, which it says have contributed immensely to the rapid exploration and exploitation of the country’s oil industry.