bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Modelling and Visualization on the Internet
Authors: Huang Bo , Worboys Michael
Published: March 2003

There is a growing requirement for GIS to incorporate dynamic analytic models. At the same time, there is a need to distribute results of dynamic GIS using the Internet. Therefore, this paper sets out to explore the implementation of dynamic environmental models using Internet‐based geocomputation techniques. An overview discusses shortcomings of current Internet GIS techniques for dynamic modelling based on the idea that bidirectional and sustained communication is required between the client and the server sides. Thus an applet‐servlet approach is explored to demonstrate the modelling process of a chosen hydrological model, TOPMODEL, which requires frequent and efficient client‐server interactions. This approach overcomes the inherent shortcomings of the current Common Gateway Interface (CGI) and more primitive Java applet techniques. We present an effective and generic way to implement dynamic modelling and visualization processes in an Internet environment. This allows users to benefit from Internet‐based geocomputation techniques to gain insights into computation and representation of dynamic spatial phenomena.
The Origins of the ‘Group Genitive’ in English
Authors: Allen Cynthia L.
Published: March 2003

The ‘group genitive’ occurring expressions such as the king of England’s daughter is first found in English texts of the late fourteenth century. In this paper, the relationship between the syncretism of cases and the appearance of this new genitive is investigated, as well as the relationship between the new construction and ‘separated genitives’ such as Adam his son. A systematic examination of Middle and Early Modern English texts yields evidence that the group genitive could not have been a reanalysis of the separated genitive, as has sometimes been suggested, and suggests that the separated genitive of Middle English was an orthographical variant of the old inflectional genitive (although a different analysis must be given for some Early Modern English texts). The evidence suggests that the group genitive developed when the old inflectional genitive (e)s was generalised to all noun classes and became reanalysed as a clitic.
EFL and EAP in the New Länder of Germany after 1989
Authors: Thürmer Uta
Published: March 2003

Since 1989, there has been an enormous increase both in the quantity and quality of EAP/ESP courses at the colleges and universities in the new Länder. This increase has been caused by several individual and institutional needs and demands, e.g., the limited command of English after school, the necessity of working with English texts at German universities, the opportunity for studying in English speaking countries, and the obligatory competence of English on a high level in the future profession. This paper shows how the LSP (language for specific purposes) centre at Dresden University has met this challenge by providing a set of courses which have been designed to meet the specific needs and demands of the students. The program includes: (1) obligatory courses in Generic Scientific English for all students of economics, engineering, information science, social and natural sciences, technology; (2) optional courses in ESP (English for specific purposes) related to the special languages of economics, science, medicine, social sciences; (3) special courses/modules aiming at the investigation and production of special text types in oral and written ESP communication. Knowledge about the English language, in particular about ESP, is incorporated in the design of all courses. Students learn about lexical, syntactical, textual properties of ESP text types and their realization by linguistic and non‐linguistic means.
Attribution and Power in Hong Kong News Discourse
Authors: Scollon Ron
Published: March 2003

The attribution of sources is situated within the broader context of social practice. Giving or withholding voice is done through the ‘same’ linguistic means, but in particular, situated cases, like means may produce significantly different outcomes. Organizing a rich interdiscursivity of practice are three forms of discursive power: (1) the power to command animation or authorship; (2) the power to give or deny voice, and (3) the power to frame discursive events. All three are found in the news discourse of Hong Kong, in English or in Chinese. What is different between these two discourses is not the exercise of power through discursive means, but the explicit focusing of that power. English or Western journalism tends to highlight the individual voices of the presenter, reporter (through bylining and delegation frames) and newsmaker (through quotation and actualities). Less clearly seen is the social and institutional power behind these voices. In Hong Kong Chinese news, one hears the voices of the news organization. Individual voices of reporters, sub‐editors, and newsmakers are backgrounded. In Hong Kong journalistic practice, social and institutional power is discursively brought into the foregound and individual speaker’s or writer’s power is set into the shadows.
The discourse and attitudes of English language teachers in Hong Kong
Authors: Tsui Amy B. M. , Bunton David
Published: March 2003

This paper suggests that Hong Kong English, insofar as it varies from Standard English, has not achieved wide acceptance in the community. The paper approaches this by investigating the attitudes of Hong Kong's English language teachers. Over a thousand messages on language issues to a computer network for English teachers were analysed, in terms of their discourse and the sources of authority the teachers referred to in support of their views on correctness or acceptability. The sources regarded as most authoritative were dictionaries and grammar or usage books from native speaking countries such as Britain. Hong Kong sources such as textbooks and the media were treated with more caution, and sometimes criticised. The model of English the teachers adopted was clearly exonormative. The term Hong Kong English did not occur anywhere in the 1,234 messages, and no deviations from a native speaker norm were referred to favourably. The paper concludes that these attitudes, similar to those in the business community, will constrain the use of Hong Kong English for formal communication.
Cultural identity profiles of Afrikaans and Southern Sotho learners of English: resource or hazard?
Authors: Rooy Susan Coetzee‐van
Published: March 2003

The cultural identity profiles of second language learners could be regarded as a resource or a hazard in the second language learning process. Constructivist theories of learning and social models of second language learning, for example, present opposing views about the usefulness of cultural identities in the learning process. The central problem investigated in this article is: should the cultural identity profiles of Afrikaans and Southern Sotho learners of English in South Africa be regarded as a resource or a hazard in the second language learning process? An empirical project was conducted in which Afrikaans and Southern Sotho respondents were requested to complete (1) a cultural identity questionnaire and (2) a standardised English second language proficiency test. Pearson Product‐Moment correlations were conducted to determine the strength and direction between the dependent (English second language proficiency score on the standardised test) and the independent variables (aspects of cultural identity). The main finding of the study is that strong in‐group identification, balanced with a more “world‐minded” disposition, and valuing social attitudes like autonomy and own lifestyle, correlated statistically significantly with higher scores on the English proficiency test for the Afrikaans and Southern Sotho participants. In the light of these findings constructs which rely upon social models of second language learning, such as integrative motivation, are therefore problematic.
Law and Gospel, or the Law of the Gospel? Karl Barth’s Political Theology Compared with Luther and Calvin
Authors: Couenhoven Jesse
Published: March 2003

This essay is an attempt to understand the significance of Barth’s redefinition of the “law/gospel” rubric for political theology. Barth’s thought is exposited at length, and illumined by comparison with Luther and Calvin. Luther emphasizes the distance between gospel and the law, distinguishing between serving God in the secular regiment, and serving Christ in the spiritual regiment. He thereby challenges the improper relation of state and church, but does so in a manner that can lead to a passive dualism. Calvin holds that preaching the law to the state includes preaching the gospel; thus, the church has a positive vision against which it can evaluate the state’s service to God in Christ. This leads, however, to the danger of a ‘clerical guardianship’ of the state.

Barth finds a positive connection between the two governments in the fact that both communities are based in Christ, in whom the gospel is their law. This grounds his high view of the state as predecessor to the heavenly kingdom, as well as a prophetic mission of the church to the state. This does not lead to a new Christendom, however, first, because Barth hopes not for a kingdom wrought by human hands, but for the Theocracy of God, and second, because Barth sees the fallen reality of both church and state, the state pagan and violent, and the church a poor witness. In the end, though Barth makes a strong case for supporting theological critique of the state, while avoiding Constantinianism, he is unable to solve the problem of how to connect the gospel and the law in the civil community.
Fitting Ethics to the Land: H. Richard Niebuhr’s Ethic of Responsibility and Ecotheology
Authors: Scoville Judith N.
Published: March 2003

Much of ecotheology and environmental philosophy has moved deductively from theological and ethical constructs to questions of how we should relate to the natural world. Such approaches are limited in their ability to guide us toward appropriate environmental action for they do not necessarily fit the way the natural world actually functions. Niebuhr’s ethic of response, on the other hand, begins with the concrete situation and is inherently ecological for it focuses on interrelationships in an on‐going community. It is inductive in character and open to being informed by new findings in the natural and social sciences; thus it is exceptionally well suited to environmental problems, which involve complex scientific, social, and economic questions.
Morality as Identity: the Missionary Moral Agenda in Buganda,1877–1945
Authors: Musisi Nakanyike B.
Published: March 2003

This article advances three arguments. First, that prior to European intrusion in the mid‐1800s, “Buganda” and “Mugandaness” were continually contested ideologies whose meanings were not given but discursively constructed and reconstructed in conditions of historical speciﬁcity. Second, that “Baganda” as an identity, was ﬁrst constructed in the early travellers’ journals. Later on missionaries and Buganda’s leading chiefs appropriated the construct “Buganda” and actively participated in its elaboration and refinement as it was later to be used and popularized in the twentieth century. Third, that Buganda identity was constructed through the active silencing of the disruptive relations of ethnicity, of gender, and of class. In the celebration of an ethnic identity, inequalities and oppression were glossed over. Out of a confrontation with the “other,” Buganda identity was carefully and powerfully articulated by the Christian middle‐class men who, from 1900, dominated the newly created ruling council of Buganda, called the Lukiiko. These men claimed to speak for the Buganda “nation” and on behalf of others. Their search for a secure identity was built on their assertion of their superiority over the “decadent” sub‐nationalities; over all non‐royal females and over all others who were not Christians, male and middle class. In examining the historical dynamics of identity, it is important to look beyond the illusion of a Buganda “Christian nation” to investigate articulations and manipulations of class, gender, ethnicity, and nationality.
Hutchinsonianism: A Counter‐Enlightenment Reform Movement
Authors: Leighton C. D. A.
Published: March 2003

The followers of the natural philosopher John Hutchinson developed a religious movement which produced one of the most notable schools of eighteenth‐century Anglican thought. This paper describes Hutchinsonianism’s position, ﬁrstly, in relation to other religious movements of the period. It sites it within a temporally speciﬁc spectrum of ecclesiastical positions and also offers a more general description of its character. To be more speciﬁc, there is discussion of the nature of the phenomenon of High Churchmanship and evangelicalism in this period and a justiﬁcation of the use of the term “reform movement.” In the latter part of the paper, Hutchinsonianism is placed within the general intellectual currents of its age. In the course of this discussion attention is drawn to previously underemphasized areas of Hutchinsonian interest, notably the history of religion. However, more importantly, this part of the paper uses Hutchinsonianism to discuss and clarify the use of the terms “Enlightenment” and “Counter‐Enlightenment” in the study of English intellectual history.
Traditional Phonics: What It Is and What It Is Not
Authors: Chew Jennifer
Published: March 2003

Recent research into the phonological aspects of children’s early reading development holds that English beginners are more aware of word‐sounds at the onset and rime level than at the individual phoneme level. A link is suspected with the comparative irregularity of English orthography. As it is widely assumed that children need to be aware of phonemes before they can benefit from a traditional phonics approach, a ‘new’ phonics or ‘rhyming analogy’ approach has been recommended as an easier route than traditional phonics for English beginning readers. This paper argues, however, that English beginners are just as capable of a phonemic approach as beginners in other languages, that phonemic awareness is not a precondition, that beliefs to the contrary are based on misunderstanding, and that systematically applying grapheme‐phoneme correspondences throughout each word is an excellent basis for word‐identification even in English. These claims are supported by test results.
Let the Emperor retain his underclothes
Authors: Stuart Morag
Published: March 2003

Scholes (1998) offers a caricature of the definition of reading, which he suggests underlies much recent psychological research. In this response, I attempt to set out a multi‐dimensional view of reading, derived from the same psychological research, which encompasses both printed word recognition skills and comprehension of written texts, and elucidates some of the relationships within and between these separable dimensions. In conclusion, I rebut Scholes’ assertion that no study has ever demonstrated a link between phonological awareness and reading comprehension.
Re‐discovering practical reading activities in homes and schools
Authors: Freebody Peter , Freiberg Jill
Published: March 2003

This paper explores issues arising from the long‐standing theoretical and empirical attention to reading as a specifiable set of psychological processes, and the consequences of this attention for parents’ and educators’ deliberations and practices. The argument is developed that these theorisations and research projects have both driven and been driven by the social and interactional configurations that teaching has traditionally been taken to entail. It then offers a critique of available theories and research findings from the perspective of ethnomethodology, along with a brief description of an ethnomethodological approach to reading as a co‐ordinated set of practical social activities. The paper proceeds to exemplify what an ethnomethodological approach could look like, through the examination of transcripts of reading sessions. The paper concludes that theories of reading need to deal fundamentally with the practices that learners, teachers and parents display as they engage in and ‘bring off’ as reading sessions, as phenomena to be explained in their own right, rather than as representations of available theories.
An investigation of reading and language abilities of college freshmen
Authors: Martino Nancy L. , Hoffman Paul R.
Published: March 2003

The purpose of this study was to compare a range of reading–related abilities in two groups of college freshmen with higher and lower reading comprehension abilities. Reading comprehension ability groups were formed using American College Test reading scores. The groups were compared on measures of oral language vocabulary and syntax, phonemic awareness and print decoding skills. Results indicated that abilities that appear to relate to reading comprehension include recognition of the order of phonemes in spoken syllables, recognition of words that are good semantic and syntactic fits for sentence frames, recall of meanings for spoken words and conversion of printed to spoken words.
Accounting for Follow-Up Bias in Estimation of Human Immunodeficiency Virus Incidence Rates
Authors: Brookmeyer R.
Published: March 2003

The objective of this paper is to describe methods for estimating current incidence rates for human immunodeficiency virus (HIV) that account for follow-up bias. Follow-up bias arises when the incidence rate among individuals in a cohort who return for follow-up is different from the incidence rate among those who do not return. The methods are based on the use of early markers of HIV infection such as p24 antigen. The first method, called the cross-sectional method, uses only data collected at an initial base-line visit. The method does not require follow-up data but does require a priori knowledge of the mean duration of the marker (μ). A confidence interval procedure is developed that accounts for uncertainty in μ. The second method combines the base-line data from all individuals together with follow-up data from those individuals who return for follow-up. This method has the distinct advantage of not requiring prior information about μ. Several confidence interval procedures for the incidence rate are compared by simulation. The methods are applied to a study in India to estimate current HIV incidence. These data suggest that the epidemic is growing rapidly in some subpopulations in India.
Clear Choices and Guesswork in Peremptory Challenges in Federal Criminal Trials
Authors: Finkelstein Michael O. , Levin Bruce
Published: March 2003

The traditional practice of permitting lawyers to strike jurors by peremptory challenge is being subjected to new questioning in the USA. Previous studies of strikes have used simulations or questionnaires, raising doubt about their relevance in actual trials. In this paper we report on a study that uses actual trial data and a mathematical model to estimate the extent to which the lawyers’ selections are clear choices on which all lawyers would agree or are guesswork involving essentially random choices. The results are that only a small proportion of the challenges are clear choices, a conclusion that is consistent with the findings of simulation studies.
Bayesian Inference for Partially Observed Stochastic Epidemics
Authors: O’Neill Philip D. , Roberts G. O.
Published: March 2003

The analysis of infectious disease data is usually complicated by the fact that real life epidemics are only partially observed. In particular, data concerning the process of infection are seldom available. Consequently, standard statistical techniques can become too complicated to implement effectively. In this paper Markov chain Monte Carlo methods are used to make inferences about the missing data as well as the unknown parameters of interest in a Bayesian framework. The methods are applied to real life data from disease outbreaks.
Spatial Variation in Teenage Conceptions in South and West England
Authors: Diamond Ian , Clements S. , Stone N. , Ingham R.
Published: March 2003

Multilevel Poisson models are used to identify factors influencing variation in census ward level teenage conception rates. Multilevel logistic models are also employed to examine the outcome of these conceptions. Demographic and socioeconomic characteristics are accounted for as well as access to family planning services. The paper emphasizes the importance of customized deprivation indices that are specific to the health outcome in urban and rural areas.
A Continuous Representation of the Family of Stable Law Distributions
Authors: Cheng R. C. H. , Liu W. B.
Published: March 2003

Conventional parametric representations of stable law distributions do not allow all members of the family to be obtained as continuous limits of the parameters. Model building (or simulation) using such representations will be numerically unstable near such limits in consequence. Existing tables are not satisfactory near such limits as interpolation cannot be carried out. We show that these difficulties are overcome by using a new shifted Cartesian representation which characterizes the entire stable law family in a completely continuous way. Standardization is still possible with this representation so that tabulation, using just two bounded parameters, can be carried out. Its use is illustrated in a non-regular threshold estimation problem involving stable distributions which are discontinuous limits in conventional representations.
Residuals for the Linear Model With General Covariance Structure
Authors: Haslett John , Hayes Kevin
Published: March 2003

A general theory is presented for residuals from the general linear model with correlated errors. It is demonstrated that there are two fundamental types of residual associated with this model, referred to here as the marginal and the conditional residual. These measure respectively the distance to the global aspects of the model as represented by the expected value and the local aspects as represented by the conditional expected value. These residuals may be multivariate. Some important dualities are developed which have simple implications for diagnostics. The results are illustrated by reference to model diagnostics in time series and in classical multivariate analysis with independent cases.
Automatic Bayesian Curve Fitting
Authors: Denison D. G. T. , Mallick B. K. , Smith A. F. M.
Published: March 2003

A method of estimating a variety of curves by a sequence of piecewise polynomials is proposed, motivated by a Bayesian model and an appropriate summary of the resulting posterior distribution. A joint distribution is set up over both the number and the position of the knots defining the piecewise polynomials. Throughout we use reversible jump Markov chain Monte Carlo methods to compute the posteriors. The methodology has been successful in giving good estimates for ‘smooth’ functions (i.e. continuous and differentiable) as well as functions which are not differentiable, and perhaps not even continuous, at a finite number of points. The methodology is extended to deal with generalized additive models.
Nonparametric Estimation of the Mode of A Distribution of Random Curves
Authors: Gasser Theo , Hall Peter , Presnell Brett
Published: March 2003

Motivated by the need to develop meaningful empirical approximations to a ‘typical’ data value, we introduce methods for density and mode estimation when data are in the form of random curves. Our approach is based on finite dimensional approximations via generalized Fourier expansions on an empirically chosen basis. The mode estimation problem is reduced to a problem of kernel-type multivariate estimation from vector data and is solved using a new recursive algorithm for finding the empirical mode. The algorithm may be used as an aid to the identification of clusters in a set of data curves. Bootstrap methods are employed to select the bandwidth.
Analysing Competing Risks Data With Transformation Models
Authors: Fine J. P.
Published: March 2003

We present a flexible class of marginal models for the cumulative incidence function. The semiparametric transformation model is utilized in a decomposition for the marginal failure probabilities which extends previous work on Farewell's cure model. Novel estimation, inference and prediction procedures are developed, with large sample properties derived from the theory of martingales and U-statistics. A small simulation study demonstrates that the methods are appropriate for practical use. The methods are illustrated with a thorough analysis of a prostate cancer clinical trial. Simple graphical displays are used to check for the goodness of fit.
On the Construction of Bayes–Confidence Regions
Authors: Sweeting Trevor J.
Published: March 2003

We obtain approximate Bayes–confidence intervals for a scalar parameter based on directed likelihood. The posterior probabilities of these intervals agree with their unconditional coverage probabilities to fourth order, and with their conditional coverage probabilities to third order. These intervals are constructed for arbitrary smooth prior distributions. A key feature of the construction is that log-likelihood derivatives beyond second order are not required, unlike the asymptotic expansions of Severini.
Covariance Structure of Wavelet Coefficients: Theory and Models in a Bayesian Perspective
Authors: Vannucci Marina , Corradi Fabio
Published: March 2003

We present theoretical results on the random wavelet coefficients covariance structure. We use simple properties of the coefficients to derive a recursive way to compute the within- and across-scale covariances. We point out a useful link between the algorithm proposed and the two-dimensional discrete wavelet transform. We then focus on Bayesian wavelet shrinkage for estimating a function from noisy data. A prior distribution is imposed on the coefficients of the unknown function. We show how our findings on the covariance structure make it possible to specify priors that take into account the full correlation between coefficients through a parsimonious number of hyperparameters. We use Markov chain Monte Carlo methods to estimate the parameters and illustrate our method on bench-mark simulated signals.
Distance Sampling Methodology
Authors: Barry Simon C. , Welsh A. H.
Published: March 2003

We consider the method of distance sampling described by Buckland, Anderson, Burnham and Laake in 1993. We explore the properties of the methodology in simple cases chosen to allow direct and accessible comparisons of distance sampling in the design- and model-based frameworks. In particular, we obtain expressions for the bias and variance of the distance sampling estimator of object density and for the expected value of the recommended analytic variance estimator within each framework. These results enable us to clarify aspects of the performance of the methodology which may be of interest to users and potential users of distance sampling.
Fitting Curves to Human Respiratory Data
Authors: Jacob G. , Marriott F. H. C. , Robbins P. A.
Published: March 2003

Records of gas flow during breathing are cyclical, with the cycles varying in duration. The shape of these cycles may change with the intensity of respiratory stimulation or the development of respiratory disease, but currently research is hampered by the lack of a fully satisfactory technique for determining the shape of a typical cycle. The approach adopted here is to replace the time series by a ‘phase diagram’, plotting the time integral of flow against flow itself. Principal curves are then fitted. These are curves ‘through the middle of the data’ which were introduced by Hastie and Stuetzle. The shapes of these curves are compared, either directly or after reconstructing an average cycle corresponding to each fitted curve. This has the advantage that the shape of the waveform is separated from the amplitude, and from the duration of the breath. A disadvantage is that periods of zero flow are lost, and the reconstructed average cycle may show irregularities at points near zero flow as a result. In practice, the methodology showed clear differences in shape between the protocols, gave reasonable average cycles and ordered the waveform shapes according to the hardness of breathing induced by the protocols.
Detecting Overdispersion in Large Scale Surveys: Application to a Study of Education and Social Class in Britain (with Comments)
Authors: Fitzmaurice Garrett M. , Heath Anthony F. , Cox D. R.
Published: March 2003

A practical problem with large scale survey data is the potential for overdispersion. Overdispersion occurs when the data display more variability than is predicted by the variance–mean relationship for the assumed sampling model. This paper describes a simple strategy for detecting and adjusting for overdispersion in large scale survey data. The method is primarily motivated by data on the relationship between social class and educational attainment obtained from a 2% sample from the 1991 census of the population of Great Britain. Overdispersion can be detected by first grouping the data into a number of strata of approximately equal size. Under the assumption that the observations are independent and there is no variability in the parameter of interest, there is a direct relationship between the nominal standard errors and the empirical or sample standard deviation of the parameter estimates obtained from each of the separate strata. With the 2% sample from the British census data, quite a discernible departure from this relationship was found, indicating overdispersion. After allowing for overdispersion, improved and more realistic measures of precision of the strength of the social class–education associations were obtained.
Mixed Inverse Problems Arising in the Estimation of Calibration Factors in Positron Emission Tomography
Authors: Pawitan Y.
Published: March 2003

A penalized likelihood approach to the estimation of calibration factors in positron emission tomography (PET) is considered, in particular the problem of estimating the efficiency of PET detectors. Varying efficiencies among the detectors create a non-uniform performance and failure to account for the non-uniformities would lead to streaks in the image, so efficient estimation of the non-uniformities is desirable to reduce the propagation of noise to the final image. The relevant data set is provided by a blank scan, where a model may be derived that depends only on the sources affecting non-uniformities: inherent variation among the detector crystals and geometric effects. Physical considerations suggest a novel mixed inverse model with random crystal effects and smooth geometric effects. Using appropriate penalty terms, the penalized maximum likelihood estimates are derived and an efficient computational algorithm utilizing the fast Fourier transform is developed. Data-driven shrinkage and smoothing parameters are chosen to minimize an estimate of the predictive loss function. Various examples indicate that the approach proposed works well computationally and compares well with the standard method.
Regression Modelling of Weighted κ by Using Generalized Estimating Equations
Authors: Gonin René , Lipsitz Stuart R. , Fitzmaurice Garett M. , Molenberghs Geert
Published: March 2003

In many clinical studies more than one observer may be rating a characteristic measured on an ordinal scale. For example, a study may involve a group of physicians rating a feature seen on a pathology specimen or a computer tomography scan. In clinical studies of this kind, the weighted κ coefficient is a popular measure of agreement for ordinally scaled ratings. Our research stems from a study in which the severity of inflammatory skin disease was rated. The investigators wished to determine and evaluate the strength of agreement between a variable number of observers taking into account patient-specific (age and gender) as well as rater-specific (whether board certified in dermatology) characteristics. This suggested modelling κ as a function of these covariates. We propose the use of generalized estimating equations to estimate the weighted κ coefficient. This approach also accommodates unbalanced data which arise when some subjects are not judged by the same set of observers. Currently an estimate of overall κ for a simple unbalanced data set without covariates involving more than two observers is unavailable. In the inflammatory skin disease study none of the covariates were significantly associated with κ, thus enabling the calculation of an overall weighted κ for this unbalanced data set. In the second motivating example (multiple sclerosis), geographic location was significantly associated with κ. In addition we also compared the results of our method with current methods of testing for heterogeneity of weighted κ coefficients across strata (geographic location) that are available for balanced data sets.
Models for Papilloma Multiplicity and Regression: Applications to Transgenic Mouse Studies
Authors: Dunson D. B.
Published: March 2003

In cancer studies that use transgenic or knockout mice, skin tumour counts are recorded over time to measure tumorigenicity. In these studies cancer biologists are interested in the effect of endogenous and/or exogenous factors on papilloma onset, multiplicity and regression. In this paper an analysis of data from a study conducted by the National Institute of Environmental Health Sciences on the effect of genetic factors on skin tumorigenesis is presented. Papilloma multiplicity and regression are modelled by using Bernoulli, Poisson and binomial latent variables, each of which can depend on covariates and previous outcomes. An EM algorithm is proposed for parameter estimation, and generalized estimating equations adjust for extra dependence between outcomes within individual animals. A Cox proportional hazards model is used to describe covariate effects on the onset of tumours.
Matched Case–Control Data Analyses with Missing Covariates
Authors: Paik Myunghee Cho , Sacco Ralph L.
Published: March 2003

We consider methods for analysing matched case–control data when some covariates (W) are completely observed but other covariates (X) are missing for some subjects. In matched case–control studies, the complete-record analysis discards completely observed subjects if none of their matching cases or controls are completely observed. We investigate an imputation estimate obtained by solving a joint estimating equation for log-odds ratios of disease and parameters in an imputation model. Imputation estimates for coefficients of W are shown to have smaller bias and mean-square error than do estimates from the complete-record analysis.
Bayesian Models for Relative Archaeological Chronology Building
Authors: Buck Caitlin E. , Sahu Sujit K.
Published: March 2003

For many years, archaeologists have postulated that the numbers of various artefact types found within excavated features should give insight about their relative dates of deposition even when stratigraphic information is not present. A typical data set used in such studies can be reported as a cross-classification table (often called an abundance matrix or, equivalently, a contingency table) of excavated features against artefact types. Each entry of the table represents the number of a particular artefact type found in a particular archaeological feature. Methodologies for attempting to identify temporal sequences on the basis of such data are commonly referred to as seriation techniques. Several different procedures for seriation including both parametric and non-parametric statistics have been used in an attempt to reconstruct relative chronological orders on the basis of such contingency tables. We develop some possible model-based approaches that might be used to aid in relative, archaeological chronology building. We use the recently developed Markov chain Monte Carlo method based on Langevin diffusions to fit some of the models proposed. Predictive Bayesian model choice techniques are then employed to ascertain which of the models that we develop are most plausible. We analyse two data sets taken from the literature on archaeological seriation.
Bayesian Models for Non‐linear Autoregressions
Authors: Müller Peter , West Mike , MacEachern Steven
Published: March 2003

We discuss classes of Bayesian mixture models for nonlinear autoregressive times series, based on developments in semiparametric Bayesian density estimation in recent years. The development involves formal classes of multivariate discrete mixture distributions, providing flexibility in modeling arbitrary nonlinearities in time series structure and a formal inferential framework within which to address the problems of inference and prediction. The models relate naturally to existing kernel and related methods, threshold models and others, although they offer major advances in terms of parameter estimation and predictive calculations. Theoretic al and computational aspects are developed here, the latter involving efficient simulation of posterior and predictive distributions. Various examples illustrate our perspectives on identification and inference using this mixture approach
Unit roots and smooth transitions
Authors: Leybourne Stephen , Newbold Paul , Vougas Dimitrios
Published: March 2003

It is common practice in time series econometrics to test the null hypothesis that the generating function is integrated—i.e. that a series is stationary only after differencing—against the alternative of stationarity about either a fixed mean or a linear trend. However, there has been considerable recent interest in the possibility of stationarity around a linear trend with an abrupt break. Here we broaden this class of alternatives to allow for a smooth transition from one trend function to another. Dickey–Fuller type tests against this alternative are developed, and their properties are explored.
An Adaptive Estimator of the Autocorrelation Coefficient in Regression Models with Autoregressive Errors
Authors: Schick Anton
Published: March 2003

In this paper an adaptive estimator of the autocorrelation coefficient is constructed in regression models whose error variables follow a stationary autoregressive process of order 1. Examples of nonparametric, additive and semiparametric regression models are discussed.
A Space‐Time Bilinear Model and its Identification
Authors: Dai Yuqing , Billard L.
Published: March 2003

In this paper we propose a class of space–time bilinear (STBL) models which can be used to model space–time series which exhibit bilinear behavior. The STBL model is shown to be an extension of a space–time autoregressive moving‐average model and a special form of the multiple bilinear model. We focus on the identification procedure of the models. Some results about stationarity and the covariance structure of these models are also discussed. An identification procedure based on the squared observations is established for the simplest pure bilinear model and some illustrative examples are provided.
The Relevance Property For Prediction Intervals
Authors: Kabaila Paul
Published: March 2003

Suppose that we have time series data which we want to use to find a prediction interval for some future value of the series. It is widely recognized by time series practitioners that, to be practically useful, a prediction interval should possess the property that it relates to what actually happened during the period that the data were collected as opposed to what might have happened during that period but did not actually happen. We call this the ‘relevance property’. Despite its obvious importance, this property has hitherto not been formulated in a mathematically rigorous way. We provide a mathematically rigorous formulation of this property for a broad class of conditionally heteroscedastic processes in the practical context that the parameters of the time series model must be estimated from the data. The importance in applications of this formulation is that it provides us with the most appropriate way of measuring the finite‐sample coverage performance of a time series prediction interval.
The Role of the Likelihood Function in the Estimation of Chaos Models
Authors: Ozaki T. , Jimenez J. C. , Haggan‐Ozaki V.
Published: March 2003

The estimation problem for chaos models defined by deterministic differential equations is discussed, and the important role of the maximum likelihood method in the inferential study of chaos models is highlighted. The usefulness of the likelihood function in the inferential study of chaos is confirmed with numerical examples from the Lorenz chaos model and the Rikitake two disk dynamo chaos model.
Functional Coefficient Autoregressive Models: Estimation and Tests of Hypotheses
Authors: Chen Rong , Liu Lon‐Mu
Published: March 2003

In this paper, we study nonparametric estimation and hypothesis testing procedures for the functional coefficient AR (FAR) models of the form Xt=f1(Xt−d)Xt− 1+ ... +fp(Xt−d)Xt−p+εt, first proposed by Chen and Tsay (1993). As a direct generalization of the linear AR model, the FAR model is a rich class of models that includes many useful parametric nonlinear time series models such as the threshold AR models of Tong (1983) and exponential AR models of Haggan and Ozaki (1981). We propose a local linear estimation procedure for estimating the coefficient functions and study its asymptotic properties. In addition, we propose two testing procedures. The first one tests whether all the coefficient functions are constant, i.e. whether the process is linear. The second one tests if all the coefficient functions are continuous, i.e. if any threshold type of nonlinearity presents in the process. The results of some simulation studies as well as a real example are presented.
S‐Estimation in the Linear Regression Model with Long‐memory Error Terms Under Trend
Authors: Sibbertsen Philipp
Published: March 2003

The asymptotic distribution of S‐estimators in the linear regression model with long‐memory error terms is obtained under mild regularity conditions to the regressors which are sufficiently weak to cover, for example, polynomial trends and i.i.d. carriers. It turns out that S‐estimators are asymptotically normal in the case of deterministic regressors with a variance–covariance structure similar to the structure in the i.i.d. case. Also, the rate of convergence for S‐estimators is the same as for the least‐squares estimator (LSE) and the best linear unbiased estimator (BLUE).
Pooled Log Periodogram Regression
Authors: SHIMOTSU KATSUMI , PHILLIPS PETER C. B.
Published: March 2003

Estimation of the memory parameter in time series with long range dependence is considered. A pooled log periodogram regression estimator is proposed that utilizes a set of mL periodogram ordinates with L→∞ rather than m ordinates as in the conventional log periodogram estimator. Consistency and asymptotic normality of the pooled regression estimator are established. The pooled estimator is shown to have smaller asymptotic variance, but larger asymptotic bias, than the conventional log periodogram estimator. Finite sample performance is assessed in simulations and the methods are illustrated in an empirical application with inflation and stock returns.
Weighted Estimation of Harmonic Components in a Musical Sound Signal
Authors: IRIZARRY RAFAEL A.
Published: March 2003

The study of musical sound has become a popular research field. Harmonic regression signal plus noise statistical models have been used to analyze sound signals. However, it is common to give estimates of harmonic parameters without indications of their uncertainties. Least squares estimates for harmonic models have been studied and asymptotic variance expression have been developed. In practice, window‐based estimates are used. This paper studies the statistical properties of such estimates; in particular, we use asymptotic variance expressions to develop standard errors and construct confidence intervals. We present applications and examples of the statistical techniques to musical sound signal analysis.
Public Financing of Education and Research in a Model of Endogenous Growth
Authors: Pelloni Alessandra
Published: March 2003

We propose a two factor endogenous growth model in which the government intervenes in the economy by financing research and/or education. We allow technology in public production to be different from technology in private production, so that public spending has a direct effect on the rental prices of factors. We characterize both the unique balanced growth path and the transitional dynamics of the model showing the steady state equilibrium to be a saddle point. We also show that while income taxation is distortive, in general, a Pareto optimal outcome can be reached by means of a consumption tax in the decentralized setting.
Pensions, Growth and Concern about the Young
Authors: Beltrametti Luca , Bonatti Luigi
Published: March 2003

Within an overlapping generations framework, we show that the proportion of old age consumption financed by a pay‐as‐you‐go system can be neutral with respect to the growth path of the economy in the presence of intergenerational transfers implemented by altruistic households or by a fiscal authority. The crucial impact on growth of society's propensity to favour the elderly is discussed. Furthermore, we offer an explanation for the existence of an authority redistributing income among generations when households are selfish. This concerns the fact that it is impossible for young agents to precommit themselves not to ask for some redistribution in their favour when old.
The Effects of Gain Sharing on the Basic Wage: The Case of IMPROSHARE
Authors: Kaufman Roger T.
Published: March 2003

Although gain‐sharing plans are typically promoted to workers as a way of increasing total compensation, workers are often concerned that gain‐sharing bonuses may become substitutes for future wage increases that would have occurred in the absence of the plan. I examine the theoretical and empirical interaction among wages, bonuses, effort, and productivity in firms that implemented IMPROSHARE, a well‐known gain‐sharing plan. Using longitudinal data obtained from a detailed survey questionnaire, I find that one can usually reject both the perfectly competitive model in which effort is held constant (in which case bonuses are a perfect substitute for wages) and the “pure gravy” model (in which bonuses completely complement the wage rate). There is no evidence that higher bonuses lead to higher relative wages. The results, however, are not very robust. Although the net effect of the bonuses on the wage rate is usually negative, it is not always statistically significant.
The Management of Redundancies in Europe: The Case of Italy
Authors: Carabelli Umberto , Ceci Anna , Ciucciovino Silvia , Tronti Leonello
Published: March 2003

The paper presents the findings of comparative and interdisciplinary legal and economic study on managing labour redundancies in seven EU member countries. It is structured for comparability between the systems examined. The introductory section contains an account of the evolution of the Italian labour market, with special reference to redundancy trends, of the features of the programmes for managing redundancies, of the roles of firms and the ‘external environment’ in handling workforce adjustments. The second section presents a map of policies that work to prevent labour redundancies (preventive measures) such as flexibility, training etc. Next, the instruments for handling temporary labour redundancies (retentive measures) are examined (e.g. short‐time working, temporary layoffs etc.). The following section is devoted to instruments and programmes involved in the management of permanent labour redundancies (expulsive measures), e.g. collective dismissals, severance pay etc. The final section provides an overall assessment of the Italian system for managing labour redundancies, and briefly discusses the national debate on the prospects for reform, in light of the principles and policies of convergence set forth by the European Union.