bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing Countries at Doha: A Political Economy Analysis
Authors: Panagariya Arvind
Published: March 2003

This paper offers a political economy analysis of the Doha Ministerial Conference with special reference to developing countries. One of my key objectives is to understand the politics underlying the negotiations with a view to assessing the influence developing countries exerted on the outcome and the success they achieved in relation to the Uruguay Round Agreement, which is widely perceived as favouring mainly if not exclusively the developed countries. The main conclusions of the paper may be summarised as follows. First, with trade liberalisation as its central focus, the Doha negotiating agenda is to be welcomed from the viewpoint of developing countries. Second, the opposition by developing countries to the inclusion of at least some of the Singapore issues at Doha is defensible. Among other things, the countries lack the necessary negotiating and implementation capacity. Third, while the UR Agreement benefited both developing and developed countries, on balance, it benefited the latter more. The Doha outcome offers a better balance when taken by itself but does not go so far as to significantly correct the imbalance in the UR Agreement. Fourth, despite this better balance, the Doha negotiations offer little evidence of a shift in the relative bargaining powers of developing and developed countries. Nor can the superficially development friendly language of the Doha Declaration be viewed as signalling the softening of the tough negotiating stance developed countries took during the UR Round. Fifth, much of the negotiating power continues to reside with developed countries. Relatively equal levels of incomes gives greater coherence to interests of developed countries on issues that divide along North–South lines. Moreover, the presence of three large players – the USA, EU and Japan – allows them to exploit their bargaining power more effectively. Finally, to negotiate more effectively in the future, developing countries must improve their research capacity, think strategically and forge coalitions with other influential WTO members – whether developed or developing.
Preparatory, Phatic and Clarification Phases in Conversational Strategies
Authors: Berendt Erich Adalbert
Published: March 2003

In order to elucidate natural spoken conversation as a genre type, the characteristics of dyadic discourse as a ‘communicative genre’ is focused on by examining the primary intent of utterances and the four phases of the dominant exchange structure via an interactive functional analysis of an extensive database of ordinary conversations (student, family and general public interaction). A distinction between language forms and the interpersonal communication purposes (both transactional and interactional) is essential in delineating the spoken language as a genre type. The Talk Day database reveals not only general characteristics on the utterance level as well as in the exchange structure but also cross‐culturally significant variation in three of the major exchange structure phases (clarification, relationship bonding and preparatory expressions). Implications for varieties of English are presented.
English language cultures in Bulgaria: a linguistic sibling rivalry?
Authors: O’Reilly Laurie M.
Published: March 2003

In the Bulgarian educational context, a complex matrix of power relations governs English language education. A triangle of international and intercultural relationships has developed. As a result of complex processes of negotiation between Bulgaria, the US, and the UK, distinct English language cultures have evolved. Yet, few studies have systematically investigated language as aid in the changing political and economic milieu of central and eastern Europe of the 1990s. In the face of this void within academic literature, this article addresses the question of how Bulgaria fits into the emerging picture of Core and Periphery English‐speaking countries.
Some syntactic features of Swazi English
Authors: Arua Arua E.
Published: March 2003

The paper describes some stable syntactic features of Swazi English. It is thus an extension and elaboration of the discussion in Kamwangamalu and Chisanga’s characterization of Swazi English. They point out that the wh‐word is placed last in question formation, time expressions such as ‘I met him last of last week’ occur and idiomatic expressions such as ‘To see once is to see twice’ are used. This paper discusses, among others, the use of the modal auxiliary must, the use of as to, the conflation of the emphatic do with the simple past tense and dangling modifiers as other stable syntactic features of Swazi English. It then elaborates on the use of idiomatic expressions, since in Kamwangamalu and Chisanga’s discussion only a few were mentioned. Finally, as there are few descriptions of Swazi English, the paper advocates more studies on the subject.
The intonation and meaning of normal yes/no questions
Authors: Levis John M.
Published: March 2003

The typical intonation of yes/no questions in American English is usually thought to be high‐rising. Accounts of yes/no questions also assume that the intonation of these questions is different from that of standard British English, which is thought to use a low‐rising intonation. This article challenges this belief and reports on a study that shows that American speakers of English do not distinguish between the high‐rising and low‐rising intonation, and argues that the supposed difference in intonation between the varieties is not accurate for yes/no questions. Finally, the results indicate that intonation of yes/no questions should be an unimportant issue in English language teaching because intonation on these questions appears to play a minimal role in the success of interactions between speakers from different varieties of English.
Linguistic Power in Virtual Communities: the Ebonics Debate on the Internet
Authors: Pandey Anjali
Published: March 2003

The recent controversy over the issue of Ebonics has been well documented in both the print media and in the electronic media, in particular, on the internet. The impact of electronic discourse has been the focus of a number of researchers (Birkerts, 1998; Lakoff, 1998; Vitanza, 1999). However, the locus of research of most theorists has been on the metalanguage of this discourse genre, and on its role in the creation of unique discourse communities (Foertsch, 1995; Hawisher and Moran, 1993). Few studies have examined the extent to which this medium functions to create and sustain group ideologies. This study presents a content analysis of the electronic debate on Ebonics that spanned over eighteen months, drawing scholars from all over the world, and culminating in over seventy individual postings on an electronic bulletin board. What this study demonstrates is that in contesting issues, using the national social debate on Ebonics, linguists seek to assert their power as a group by excluding and marginalizing those parties that do not belong. The data analysis illustrates the linguistic devices through which such othering is constructed and maintained. The resultant electronic debate while overtly framed about Ebonics, covertly functions to assert the status of linguists as a group.
Liberalism and Collective Investments in Repertoires
Authors: Stinchcombe A. L.
Published: March 2003

The true end of Man . . . is the highest and most harmonious development of his powers to a complete and consistent whole. Freedom is the first and indispensable condition which the possibility of such a development presupposes; but there is besides another essential—intimately connected with freedom, it is true—a variety of situations. Even the most free and self‐reliant of men is hindered in his development, when set in a monotonous situation.—Wilhelm von Humboldt
Measuring Transition and Mobility in the Hierarchical World–Economy
Authors: Dezzani Raymond J.
Published: March 2003

This paper provides a temporal stochastic framework that is used to analyze economic transitions of countries in the world–system. As such, it provides a contribution to a general quantitative rendering of the world–systems perspective. State space modeling using Markov chains provides a powerful stochastic instrument for global economic modeling when structure is known but relational uncertainty is present as well as for examining temporal change of geographic phenomena. Two phenomena are examined: (1) country mobility among regional classes within the world–economy; and (2) the stability of the rate of country–level transitions. Results suggest that although a moderate amount of movement has taken place in the period 1960–1990, the overall structure of the world–economy has not changed significantly. Thus, although the developmental hypothesis that countries are upwardly mobile has merit, empirical results suggest that very little impact is observed in the world–system because countries moving upward in the world–economy region sequence are nearly balanced by countries moving down the sequence.
Where Have All the Proportionalists Gone?
Authors: Kalbian Aline H.
Published: March 2003

Interest in proportionalism as an important trend in Catholic moral theology seems to have faded in the recent decade. This has led some to view it as a movement that was somehow defeated. I suggest that proportionalism’s influence can still be seen in contemporary Catholic ethics, most noticeably in the current interest in virtue ethics, casuistry, and feminist ethics. I argue that proportionalism encouraged a reappraisal of the methodology for evaluating moral action in a direction that was more hospitable to concerns about the particularity and context of the agent.
Reasonably Traditional: Self–Contradiction and Self–Reference in Alasdair MacIntyre’s Account of Tradition–Based Rationality
Authors: Lott Micah
Published: March 2003

Alasdair MacIntyre’s account of tradition–based rationality has been the subject of much discussion, as well as the object of some recent charges of inconsistency. The author considers arguments by Jennifer Herdt, Peter Mehl, and John Haldane which attempt to show that MacIntyre’s account of rationality is, in some way, inconsistent. It is argued that the various charges of inconsistency brought against MacIntyre by these critics can be understood as variations on two general types of criticism: (1) that MacIntyre’s account of tradition–based rationality presents a picture of rationality with inconsistent internal elements, and (2) that MacIntyre, in the act of presenting his picture of rationality, makes the sort of claims to which his own account of rationality denies legitimacy, and thus MacIntyre’s account is self–referentially incoherent. In response to criticisms of the first sort, it is argued that MacIntyre can further clarify or develop his position to take the current criticisms into account without altering the fundamental aspects of his picture of rationality. In response to the charge of self–referential incoherence, it is argued that the charge rests on a mistaken understanding of MacIntyre’s position and of the nature of justification. In dealing with these arguments, the author hopes to not only vindicate MacIntyre’s account of rationality against the charges of some of its recent critics, but also to shed some light on the nature of arguments both for and against relativism and historicism.
German “Non‐Aryan” Clergymen and the Anguish of Exile After 1933
Authors: Webster Ronald D.E.
Published: March 2003

This paper provides a commentary on the archival and oral sources relating to the lives in exile of a group of “non‐Aryan” German pastors who, on the eve of World War II, emigrated to the United Kingdom, Canada, and the United States to escape the cruel and arbitrary anti‐Semitic laws of Nazi Germany. It pays some homage to the work of those who assisted the refugees, from the seminal efforts of Bishop George Bell of Chichester, to the lesser known but significant activities of Pastor Hermann Maas of Heidelberg, Emmanuel Poppen of the American Lutheran Church, Dietrich Bonhoeffer and Martin Niemöller. In addition, the paper explores the ways in which the testimonies of this interesting group open a window onto many intriguing questions relating to religious identity, personal response to the trauma of war, and the ongoing dialogue between Judaism and Christianity.
The Prelingually Deaf Young Reader: A Case of Reliance on Direct Lexical Access?
Authors: Beech John R. , Harris Margaret
Published: March 2003

A comparison was made between prelingually deaf and hearing children matched on reading age (between 7:0 and 7:11 years) in order to examine possible differences in reading performance. The deaf children all had a severe or profound hearing loss and were receiving special education in either a school or a unit for the deaf. The experimental tasks used a lexical decision task involving the reading of single words. The employment of phonology in reading was investigated by comparing reading performance on regular and irregular words and by comparing reading of homophonic versus non–homophonic nonwords. Both tasks revealed that hearing participants were much more affected by regularity and homophony, suggesting a much greater reliance on assembled phonological recoding. These results are discussed in terms of deaf readers relying on lexical access for reading print.
The role of interest and text structure in professional reading
Authors: Spooren Wilbert , Mulder Monique , Hoeken Hans
Published: March 2003

Students can be regarded as professional readers: they have to attend to, comprehend and remember the most important information in instructional texts, often about topics they are not readily interested in. Optimising such instructional texts has been the subject of much reading research. This research has shown robust effects for the influence of text structure: information highlighted by a strongly organising structure is retained better than seemingly less important information. Hidi and Baird (1986) suggest that such effects of structure are artefacts, because of the dullness of texts used in such experiments. They argue that readers mainly use interest instead of structure as their guide for attention and learning. In this article three related experiments using Dutch instructional texts are reported. Both interest and text structure were manipulated as within‐item factors, and on‐line as well as off‐line methods were used to measure effects on the reading process and product. The outcomes show no support for the hypothesis of Hidi and Baird: students learn better from texts that are well structured, regardless of the interest of the text or its topic.
Pupils’ reading is better in schools with a librarian: evidence from Slovenia (Research Note)
Authors: Novljan Silva
Published: March 2003

Using data from a representative sample of schools that participated in the IEA International Literacy Study, the importance of the librarian’s contribution to the development of reading was investigated by comparing the reading test results of pupils who did not have access to a professional school librarian. The mean reading test scores obtained by pupils in schools employing a professional librarian (n=86) were found to be significantly higher than those obtained in schools where a teacher was responsible for the school library (n=50).T
National survey of reading comprehension in Finland
Authors: Lehto Juhani , Scheinin Patrik , Kupiainen Sirkku , Hautamäki Jarkko
Published: March 2003

As a part of an extensive project for the evaluation of the Finnish comprehensive school, a recently developed reading comprehension measure; a hierarchy‐rating test, and a more conventional multiple‐choice task were used to assess reading comprehension skills in population‐based samples of 2,891 sixth‐graders (12–13 years old) and 1,953 (15–16 years old) ninth‐graders. The hierarchy‐rating task was constructed within the theoretical framework proposed by W. Kintsch and van Dijk (1978). It was designed to examine the cognitively high‐level text processing, or macroprocessing, of expository passages. The multiple‐choice task and the hierarchy‐rating task showed only a moderate intercorrelation. Girls outperformed boys regardless of the comprehension measure. Performance on both measures, but particularly on hierarchy‐rating, correlated with school achievement (r=0.44 and 0.53 respectively, p<0.001). In general, the results are in agreement with previous research. The paper also discusses the educational implications of the survey.
Discovering EFL learners’ perception of prior knowledge and its roles in reading comprehension
Authors: Lin Zheng
Published: March 2003

This paper investigates EFL learners’ perception of prior knowledge and its roles in reading comprehension. It is based on a survey conducted among 400 EFL students studying at secondary and tertiary levels in China. Through the analysis of the ranked multiple responses to the questions posed in the questionnaire, the paper shows that EFL students in mainland China believe that their command of English vocabulary plays a crucial role in their reading comprehension. However as their linguistic knowledge increases, they tend to attach less importance to their linguistic knowledge, especially the knowledge of English syntax and formal structures. At the same time, conceptual and sociocultural knowledge seems to gain greater importance. Furthermore, the perceived importance of linguistic knowledge seems to start diminishing around the end of secondary education, when EFL students have acquired a vocabulary of about 3000 words and the basic knowledge of English syntax and formal structures. The final replacement of linguistic knowledge by conceptual or sociocultural knowledge as the top factor that affects their reading comprehension seems to take place one year after the beginning of the tertiary EFL course. This may well be considered as an indication of the EFL threshold level for EFL students in China.
Reader question formation as a tool for measuring comprehension: narrative and expository textual inferences in a second language
Authors: DuBravac Stayc , Dalle Mathieu
Published: March 2003

Psychological models of first language (L1) textual comprehension distinguish between expository and narrative texts but are unclear on differences of inference generation between the two types of texts in a second language (L2). Forty‐seven undergraduate students performed a comprehension task using two narrative and two expository texts in an L2. Participants generated questions at specific points throughout each text. Responses were categorised under six question types: scripturally implicit, textually implicit, textually explicit, linguistic and miscomprehension. Results showed that subjects generated more inferences for narrative texts while exhibiting more miscomprehension for expository texts.
Scenarios, Uncertainty and Conditional Forecasts of the World Population
Authors: Alho Juha M.
Published: March 2003

Current official population forecasts differ little from those that Whelpton made 50 years ago either in the cohort–component methodology used or in the arguments used to motivate the assumptions. However, Whelpton produced some of the most erroneous forecasts of this century. This suggests that current forecasters should ensure that they give users an assessment of the uncertainty of their forecasts. We show how simple statistical methods can be combined with expert judgment to arrive at an overall predictive distribution for the future population. We apply the methods to a world population forecast that was made in 1994. Accepting that point forecast, we find that the probability is only about 2% that the world population in the year 2030 will be less than the low scenario of 8317 million. The probability that the world population will exceed the high scenario of 10 736 million is about 13%. Similarly, the probability is only about 51% that the high–low interval of a recent United Nations (UN) forecast will contain the true population in the year 2025. Even if we consider the UN high–low intervals as conditional on the possible future policies of its member states, they appear to have a relatively small probability of encompassing the future population.
Stochastic Models of Geriatric Patient Bed Occupancy Behaviour
Authors: Taylor G. J. , McClean S. I. , Millard P. H.
Published: March 2003

This paper considers a census approach to the modelling of the time that geriatric patients spend in hospital and subsequently in the community by using a stochastic compartmental Markov model. A selection process is developed using maximum likelihood estimation to fit the model to daily census data on the duration spent in the hospital or the community. Census data are used as they are easy to collect and therefore maximize the usability of the model. The model is fitted to an extensive 16-year data-set and shown to provide realistic estimates of movements of patients by using only a single day’s census result.
The Cluster That Never Was: Germ Warfare Experiments and Health Authority Reality in Dorset
Authors: Stein C. E. , Bennett S. , Crook S. , Maddison F.
Published: March 2003

In 1997 intense media coverage raised public concerns about germ warfare simulation experiments conducted by the Ministry of Defence during the 1960s, which included the release of bacteria over Dorset. Families in East Lulworth, Dorset, have linked this with allegedly high rates of miscarriages, still-births, congenital malformations, learning and other neurodevelopmental disabilities in their village. The response of the Dorset Health Authority (DHA) included the examination of background information from the Ministry of Defence, national data on congenital malformations in Dorset, health information collected by campaigners and a systematic health survey conducted by the DHA among former and current residents of East Lulworth. The investigation did not confirm the presence of a cluster. It is debatable whether the DHA should have proceeded with their survey when none of the other more immediately available results indicated the presence of a cluster.
Estimation of Life Expectancy in the Middle Ages
Authors: Jonker M. A.
Published: March 2003

In the Middle Ages data on landholders were recorded. We use a selection of these data for estimating the life expectancy of adult males from the higher ranks of English society. The data consist of the age at which the landholder inherited land, a sequence of ages at which he was known to be alive and possibly the age at death. We explain that the date of death is left truncated and right censored at an unknown censoring time. We propose a model to fit (a selection of) the data, we give estimators of the unknown parameters in the model and we present estimates of adult life expectancy.
Weighted Mean Survival Test Statistics: A Class of Distance Tests for Censored Survival Data
Authors: Shen Yu , Fleming Thomas R.
Published: March 2003

A class of test statistics is introduced which is sensitive against the alternative of stochastic ordering in the two-sample censored data problem. The test statistics for evaluating a cumulative weighted difference in survival distributions are developed while taking into account the imbalances in base-line covariates between two groups. This procedure can be used to test the null hypothesis of no treatment effect, especially when base-line hazards cross and prognostic covariates need to be adjusted. The statistics are semiparametric, not rank based, and can be written as integrated weighted differences in estimated survival functions, where these survival estimates are adjusted for covariate imbalances. The asymptotic distribution theory of the tests is developed, yielding test procedures that are shown to be consistent under a fixed alternative. The choice of weight function is discussed and relies on stability and interpretability considerations. An example taken from a clinical trial for acquired immune deficiency syndrome is presented.
Updating Schemes, Correlation Structure, Blocking and Parameterization for the Gibbs Sampler
Authors: Roberts G. O. , Sahu S. K.
Published: March 2003

In this paper many convergence issues concerning the implementation of the Gibbs sampler are investigated. Exact computable rates of convergence for Gaussian target distributions are obtained. Different random and non-random updating strategies and blocking combinations are compared using the rates. The effect of dimensionality and correlation structure on the convergence rates are studied. Some examples are considered to demonstrate the results. For a Gaussian image analysis problem several updating strategies are described and compared. For problems in Bayesian linear models several possible parameterizations are analysed in terms of their convergence rates characterizing the optimal choice.
Estimation of the Distribution Function of a Standardized Statistic
Authors: Lee Stephen M. S. , Young G. Alastair
Published: March 2003

For estimating the distribution of a standardized statistic, the bootstrap estimate is known to be local asymptotic minimax. Various computational techniques have been developed to improve on the simulation efficiency of uniform resampling, the standard Monte Carlo approach to approximating the bootstrap estimate. Two new approaches are proposed which give accurate yet simple approximations to the bootstrap estimate. The second of the approaches even improves the convergence rate of the simulation error. A simulation study examines the performance of these two approaches in comparison with other modified bootstrap estimates.
Optimal Bayesian Randomization
Authors: Berry Scott M. , Kadane Joseph B.
Published: March 2003

Randomization is a puzzle for Bayesians. The intuitive need for randomization is clear, but there is a standard result that Bayesians need not randomize. In this paper we propose a model in which randomization is a strictly optimal procedure. The most important aspect of our model is that there are several parties who make different decisions and observe different data. The result also sheds light on the ethical considerations involving randomization in a clinical trial.
Bayesian Versus Frequentist Measures of Error in Small Area Estimation
Authors: Singh A. C. , Stukel D. M. , Pfeffermann D.
Published: March 2003

This paper compares analytically and empirically the frequentist and Bayesian measures of error in small area estimation. The model postulated is the nested error regression model which allows for random small area effects to represent the joint effect of small area characteristics that are not accounted for by the fixed regressor variables. When the variance components are known, then, under a uniform prior for the regression coefficients and normality of the error terms, the frequentist and the Bayesian approaches yield the same predictors and prediction mean-squared errors (MSEs) (defined accordingly). When the variance components are unknown, it is common practice to replace the unknown variances by sample estimates in the expressions for the optimal predictors, so that the resulting empirical predictors remain the same under the two approaches. The use of this paradigm requires, however, modifications to the expressions of the prediction MSE to account for the extra variability induced by the need to estimate the variance components. The main focus of this paper is to review and compare the modifications to prediction MSEs proposed in the literature under the two approaches, with special emphasis on the orders of the bias of the resulting approximations to the true MSEs. Some new approximations based on Monte Carlo simulation are also proposed and compared with the existing methods. The advantage of these approximations is their simplicity and generality. Finite sample frequentist properties of the various methods are explored by a simulation study. The main conclusions of this study are that the use of second-order bias corrections generally yields better results in terms of the bias of the MSE approximations and the coverage properties of confidence intervals for the small area means. The Bayesian methods are found to have good frequentist properties, but they can be inferior to the frequentist methods. The second-order approximations under both approaches have, however, larger variances than the corresponding first-order approximations which in most cases result in higher MSEs of the MSE approximations.
Bayesian Image Analysis With Markov Chain Monte Carlo and Coloured Continuum Triangulation Models
Authors: Nicholls Geoff K.
Published: March 2003

It is now possible to carry out Bayesian image segmentation from a continuum parametric model with an unknown number of regions. However, few suitable parametric models exist. We set out to model processes which have realizations that are naturally described by coloured planar triangulations. Triangulations are already used, to represent image structure in machine vision, and in finite element analysis, for domain decomposition. However, no normalizable parametric model, with realizations that are coloured triangulations, has been specified to date. We show how this must be done, and in particular we prove that a normalizable measure on the space of triangulations in the interior of a fixed simple polygon derives from a Poisson point process of vertices. We show how such models may be analysed by using Markov chain Monte Carlo methods and we present two case-studies, including convergence analysis.
Testing Heteroscedasticity In Nonparametric Regression
Authors: Dette Holger , Munk Axel
Published: March 2003

The importance of being able to detect heteroscedasticity in regression is widely recognized because efficient inference for the regression function requires that heteroscedasticity is taken into account. In this paper a simple consistent test for heteroscedasticity is proposed in a nonparametric regression set-up. The test is based on an estimator for the best L  2-approximation of the variance function by a constant. Under mild assumptions asymptotic normality of the corresponding test statistic is established even under arbitrary fixed alternatives. Confidence intervals are obtained for a corresponding measure of heteroscedasticity. The finite sample performance and robustness of these procedures are investigated in a simulation study and Box-type corrections are suggested for small sample sizes.
On Efficient Point Prediction Systems
Authors: Skouras Kostas , Dawid A. Philip
Published: March 2003

Assume that a forecaster observes a sequence of random variables and issues predictions according to a point prediction systems, i.e. a rule which, at every time t, issues a point prediction for the next observation at time t+1. We introduce the concept of efficiency of a point prediction system, for the case that the joint distribution of the sequence of observations is known to belong to a parametric family, and performance is assessed by the long run sum of squared prediction errors. Independence is not a requirement. Under weak conditions, the class of efficient point prediction systems is non-empty, and any two efficient point prediction systems will, in a certain strong sense, make asymptotically identical predictions for the infinite future. We discuss the efficiency of point prediction systems based on Bayesian predictive means, and on plugging in parameter estimates. The results are applied to probability forecasting and stochastic regression.
Bayesian Inference for Semiparametric Regression Using a Fourier Representation
Authors: Lenk Peter J.
Published: March 2003

This paper presents the Bayesian analysis of a semiparametric regression model that consists of parametric and nonparametric components. The nonparametric component is represented with a Fourier series where the Fourier coefficients are assumed a priori to have zero means and to decay to 0 in probability at either algebraic or geometric rates. The rate of decay controls the smoothness of the response function. The posterior analysis automatically selects the amount of smoothing that is coherent with the model and data. Posterior probabilities of the parametric and semiparametric models provide a method for testing the parametric model against a non-specific alternative. The Bayes estimator’s mean integrated squared error compares favourably with the theoretically optimal estimator for kernel regression.
Confidence Intervals for Secondary Parameters Following a Sequential Test
Authors: Whitehead John , Todd Susan , Hall W. J.
Published: March 2003

In sequential studies, formal interim analyses are usually restricted to a consideration of a single null hypothesis concerning a single parameter of interest. Valid frequentist methods of hypothesis testing and of point and interval estimation for the primary parameter have already been devised for use at the end of such a study. However, the completed data set may warrant a more detailed analysis, involving the estimation of parameters corresponding to effects that were not used to determine when to stop, and yet correlated with those that were. This paper describes methods for setting confidence intervals for secondary parameters in a way which provides the correct coverage probability in repeated frequentist realizations of the sequential design used. The method assumes that information accumulates on the primary and secondary parameters at proportional rates. This requirement will be valid in many potential applications, but only in limited situations in survival analysis.
Influence Analysis Based on the Case Sensitivity Function
Authors: Critchley Frank , Atkinson Richard A. , Lu Guobing , Biazi Elenice
Published: March 2003

The case sensitivity function approach to influence analysis is introduced as a natural smooth extension of influence curve methodology in which both the insights of geometry and the power of (convex) analysis are available. In it, perturbation is defined as movement between probability vectors defining weighted empirical distributions. A Euclidean geometry is proposed giving such perturbations both size and direction. The notion of the salience of a perturbation is emphasized. This approach has several benefits. A general probability case weight analysis results. Answers to a number of outstanding questions follow directly. Rescaled versions of the three usual finite sample influence curve measures—seen now to be required for comparability across different-sized subsets of cases—are readily available. These new diagnostics directly measure the salience of the (infinitesimal) perturbations involved. Their essential unity, both within and between subsets, is evident geometrically. Finally it is shown how a relaxation strategy, in which a high dimensional (O(nCm)) discrete problem is replaced by a low dimensional (O(n)) continuous problem, can combine with (convex) optimization results to deliver better performance in challenging multiple-case influence problems. Further developments are briefly indicated.
Local Likelihood Tracking of Fault Lines and Boundaries
Authors: Hall Peter , Peng Liang , Rau Christian
Published: March 2003

We suggest locally parametric methods for estimating curves, such as boundaries of density supports or fault lines in response surfaces, in a variety of spatial problems. The methods are based on spatial approximations to the local likelihood that the curve passes through a given point in the plane, as a function of that point. The local likelihood might be a regular likelihood computed locally, with kernel weights (e.g. in the case of support boundary estimation) or a local version of a likelihood ratio statistic (e.g. in fault line estimation). In either case, the local likelihood surface represents a function which is relatively large near the target curve, and relatively small elsewhere. Therefore, the curve may be estimated as a ridge line of the surface; we require only a numerical algorithm for tracking the projection of a ridge into the plane. This approach offers several potential advantages over alternative methods. First, the local (log-)likelihood surface can be graphed, and the degree of ‘ridginess’ assessed visually, to determine how the level of local smoothing should be varied in different spatial locations in order to emphasize the ridge and hence the curve adequately. Secondly, the local likelihood surface does not need to be computed in anything like its entirety; once we have a reasonable approximation to a point on the curve we may track it by numerically ‘walking along’ the ridge line. Thirdly, the method is appropriate without change for many different types of spatial explanatory variables—gridded, stochastic or otherwise. Three examples are explored in detail; fault lines in response surfaces and in intensity or density surfaces, and boundaries of supports of probability densities.
A General Method of Constructing E(s2)-Optimal Supersaturated Designs
Authors: Butler Neil A. , Mead Roger , Eskridge Kent M. , Gilmour Steven G.
Published: March 2003

There has been much recent interest in supersaturated designs and their application in factor screening experiments. Supersaturated designs have mainly been constructed by using the E(s2)-optimality criterion originally proposed by Booth and Cox in 1962. However, until now E(s2)-optimal designs have only been established with certainty for n experimental runs when the number of factors m is a multiple of n-1, and in adjacent cases where m=q( n-1) +r (|r|⩽2, q an integer). A method of constructing E(s2)-optimal designs is presented which allows a reasonably complete solution to be found for various numbers of runs n including n,=8 12, 16, 20, 24, 32, 40, 48, 64.
Efficient Calculation of the Normalizing Constant of the Autologistic and Related Models on the Cylinder and Lattice
Authors: Pettitt A. N. , Friel N. , Reeves R.
Published: March 2003

Motivated by the autologistic model for the analysis of spatial binary data on the two-dimensional lattice, we develop efficient computational methods for calculating the normalizing constant for models for discrete data defined on the cylinder and lattice. Because the normalizing constant is generally unknown analytically, statisticians have developed various ad hoc methods to overcome this difficulty. Our aim is to provide computationally and statistically efficient methods for calculating the normalizing constant so that efficient likelihood-based statistical methods are then available for inference. We extend the so-called transition method to find a feasible computational method of obtaining the normalizing constant for the cylinder boundary condition. To extend the result to the free-boundary condition on the lattice we use an efficient path sampling Markov chain Monte Carlo scheme. The methods are generally applicable to association patterns other than spatial, such as clustered binary data, and to variables taking three or more values described by, for example, Potts models.
Circuit Optimization via Sequential Computer Experiments: Design of an Output Buffer
Authors: Aslett Robert , Buck Robert J. , Duvall Steven G. , Sacks Jerome , Welch William J.
Published: March 2003

In electrical engineering, circuit designs are now often optimized via circuit simulation computer models. Typically, many response variables characterize the circuit’s performance. Each response is a function of many input variables, including factors that can be set in the engineering design and noise factors representing manufacturing conditions. We describe a modelling approach which is appropriate for the simulator’s deterministic input–output relationships. Non-linearities and interactions are identified without explicit assumptions about the functional form. These models lead to predictors to guide the reduction of the ranges of the designable factors in a sequence of experiments. Ultimately, the predictors are used to optimize the engineering design. We also show how a visualization of the fitted relationships facilitates an understanding of the engineering trade-offs between responses. The example used to demonstrate these methods, the design of a buffer circuit, has multiple targets for the responses, representing different trade-offs between the key performance measures.
Comparison of Two Smoothing Methods for Exploring Waning Vaccine Effects
Authors: Durham L. Kathryn , Halloran M. Elizabeth , Longini Ira M. , Manatunga Amita K.
Published: March 2003

We consider the statistical evaluation and estimation of vaccine efficacy when the protective effect wanes with time. We reanalyse data from a 5-year trial of two oral cholera vaccines in Matlab, Bangladesh. In this field trial, one vaccine appears to confer better initial protection than the other, but neither appears to offer protection for a period longer than about 3 years. Time-dependent vaccine effects are estimated by obtaining smooth estimates of a time-varying relative risk RR(t) using survival analysis. We compare two approaches based on the Cox model in terms of their strategies for detecting time-varying vaccine effects, and their estimation techniques for obtaining a time-dependent RR(t) estimate. These methods allow an exploration of time-varying vaccine effects while making minimal parametric assumptions about the functional form of RR(t) for vaccinated compared wit unvaccinated subjects.
A Family of Models for Uniform and Serial Dependence in Repeated Measurements Studies
Authors: Lindsey J. K.
Published: March 2003

Data arising from a randomized double-masked clinical trial for multiple sclerosis have provided particularly variable longitudinal repeated measurements responses. Specific models for such data, other than those based on the multivariate normal distribution, would be a valuable addition to the applied statistician’s toolbox. A useful family of multivariate distributions can be generated by substituting the integrated intensity of one distribution into a second (outer) distribution. The parameters in the second distribution are then used to create a dependence structure among observations on a unit. These may either be a form of serial dependence for longitudinal data or of uniform dependence within clusters. These are respectively analogous to the Kalman filter of state space models and to copulas, but they have the major advantage that they do not require any explicit integration. One useful outer distribution for constructing such multivariate distributions is the Pareto distribution. Certain special models based on it have previously been used in event history analysis, but those considered here have much wider application.
Binary Probability Maps Using a Hidden Conditional Autoregressive Gaussian Process with an Application to Finnish Common Toad Data
Authors: Weir I. S. , Pettitt A. N.
Published: March 2003

The Finnish common toad data of Heikkinen and Hogmander are reanalysed using an alternative fully Bayesian model that does not require a pseudolikelihood approximation and an alternative prior distribution for the true presence or absence status of toads in each 10 km×10 km square. Markov chain Monte Carlo methods are used to obtain posterior probability estimates of the square-specific presences of the common toad and these are presented as a map. The results are different from those of Heikkinen and Hogmander and we offer an explanation in terms of the prior used for square-specific presence of the toads. We suggest that our approach is more faithful to the data and avoids unnecessary confounding of effects. We demonstrate how to extend our model efficiently with square-specific covariates and illustrate this by introducing deterministic spatial changes.
Bayesian Incidence Analysis of Animal Tumorigenicity Data
Authors: Dunson D. B. , Dinse G. E.
Published: March 2003

Statistical inference about tumorigenesis should focus on the tumour incidence rate. Unfortunately, in most animal carcinogenicity experiments, tumours are not observable in live animals and censoring of the tumour onset times is informative. In this paper, we propose a Bayesian method for analysing data from such studies. Our approach focuses on the incidence of tumours and accommodates occult tumours and censored onset times without restricting tumour lethality, relying on cause-of-death data, or requiring interim sacrifices. We represent the underlying state of nature by a multistate stochastic process and assume general probit models for the time-specific transition rates. These models allow the incorporation of covariates, historical control data and subjective prior information. The inherent flexibility of this approach facilitates the interpretation of results, particularly when the sample size is small or the data are sparse. We use a Gibbs sampler to estimate the relevant posterior distributions. The methods proposed are applied to data from a US National Toxicology Program carcinogenicity study.
A Parametric approach to testing the null of cointegration
Authors: McCabe B. P. M. , Leybourne S. J. , Shin Y.
Published: March 2003

A residual‐based test for cointegration is proposed where a parametric adjustment is made to account for the possible stationarity of the disturbance vector. Allowance is also made for the regressor variables to be cointegrated among themselves. The parametric adjustment turns out to be more robust and powerful than tests based on long‐run variance estimators according to theoretical and simulation evidence.
On backward periodic autoregressive processes
Authors: Sakai Hideaki , Ohno Shyuichi
Published: March 2003

It has been shown that there is a one‐to‐one correspondence between a multivariate autoregress ive (AR) process and a scalar periodic AR process. So we can analyze periodic processes by the theory of multivariate AR processes and vice versa.

Multivariate AR processes have been widely studied and the Levinson–Whittle–Wiggins–Robinson algorithm is well known for obtaining the predictor coeffic ient matrices. In addition, the circular Levinson algorithm has been derived for obtaining the coefficients of periodic AR processes.

In this paper, we construct backward periodic AR processes from the auxiliary coefficients used in this algorithm. A numerical example is also presented and the statistical properties of the estimated coefficients of backward periodic AR processes based on a sample of finite size are derived.
On Residual Variance Estimation in Autoregressive Models
Authors: Mentz Raul P. , Morettin Pedro A. , Toloi Clélia
Published: March 2003

In this paper we consider time series models belonging to the autoregressive (AR) family and deal with the estimation of the residual variance. This is important because estimates of the variance are involved in, for example, confidence sets for the parameters of the model, estimation of the spectrum, expressions for the estimated error of prediction and sample quantities used to make inferences about the order of the model. We consider the asymptotic biases for moment and least squares estimators of the residual variance, and compare them with known results when available and with those for maximum likelihood estimators under normality. Simulation results are presented for finite samples
Book Review
Authors: Basawa Iswar
Published: March 2003

B. M. Potscher and I. R. Prucha,Dynamic Nonlinear Econometric Models, Asymptotic Theory
Bartlett Corrections for Unit Root Test Statistics
Authors: Larsson Rolf
Published: March 2003

Bartlett corrections of the log likelihood ratio test for a unit root in an AR(1) process, as well as for some asymptotically equivalent tests, are studied. The corrections are obtained by an analytical method. The numerical performance of the results is checked in a simulation study.
Unit Root Tests Based on Unconditional Maximum Likelihood Estimation for the Autoregressive Moving Average
Authors: Shin Dong Wan , Fuller Wayne
Published: March 2003

Unconditional maximum likelihood estimation is considered for an autoregressive moving average that may contain an autoregressive unit root. The limiting distribution of the normalized maximum likelihood estimator of the unit root is shown to be the same as that of the estimator for the first‐order autoregressive process. A likelihood ratio test based on unconditional maximum likelihood estimation is proposed. In a Monte Carlo study for the autoregressive moving‐average model of order (1, 1), the new test is shown to have better size and power than those of several other tests.