bluuebunny/crossref_metadata_2025_split huggingface dataset:
Confidence Intervals for Secondary Parameters Following a Sequential Test
Authors: Whitehead John , Todd Susan , Hall W. J. 
Published: March 2003

Summary
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

Summary
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

Summary
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

Summary
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

SummaryMotivated 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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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.
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.
What is Meant by ‘What is Said’? A Reply to Cappelen and Lepore
Authors: Reimer Marga 
Published: March 2003

In a recent paper Herman Cappelen and Ernie Lepore challenge an assumption that they rightly claim is pervasive among contemporary philosophers of language. According to this assumption (MA), an adequate semantic theory T fora language L should assign p as the semantic content of a sentence S in L if and only if in uttering S a speaker says that p. I claim that the arguments of Cappelen and Lepore are based upon an uncharitable interpretation of MA. If ‘saying’ is understood in a roughly Gricean sense, MA emerges as an eminently plausible assumption.
Arguing Anselm's Argument
Authors: Overton John 
Published: March 2003

Interpretation surrounding Saint Anselm's celebrated Proslogion often divides across analytical (philosophical) and non‐analytical (historical, phenomenological, etc.) lines, with focus on the argument(s) of Chapters 2 and 3 isolated from the rest of the text. Interpretations may vary significantly, but the lines of interpretation continue along these divisions, thus propagating the distinction. Alternative tools, however, expose difficulties of such a division of the Proslogion; they permit analytical justification of claims, concerns and intuitions of historical, phenomenological, and other interests, implicating a more complex re‐interpretation of the presuppositions supporting the isolation of Chapters 2 and 3.Based on an approach to reading developed from semiotics and text linguistics, this analysis challenges the major line of analytic interpretation of the Proslogion. This paper argues that the Proslogion has a structure different from the previously realized one, and that the structure consists of three nested frameworks within a devotional whole, faith leading the heart to illuminate the intellect, which in turn can grasp the syllogisms of chapters 2–3/4. Such a textual structure suggests strongly different conclusions about the core significance, utility, and meaning of the Proslogion as ”argument“.
The impact of emissions trading on OPEC
Authors: Ghanem Shokri , Lounnas Rezki , Brennand Garry 
Published: March 2003

The latest reference case from OPEC’s World Energy Model, OWEM, sees world oil demand growing to 88 million barrels per day by 2010 and increasing by a further 11 mb/d to 99 mb/d by 2020. With the growth in oil production from developing countries and Russia offset by a secular decline in OECD production, OPEC is set to increasingly supply the incremental barrel, with production rising to 40 mb/d by 2010 and 51 mb/d by 2020.Against the backdrop of this reference case, this paper considers the implications of measures to reduce the emissions of greenhouse gases (GHGs), in accordance with the Kyoto Protocol.The initial scenario assumes that three OECD regions each impose a carbon tax that is sufficient to reach their own Kyoto emissions targets, resulting in a fall in OECD demand of 6.5 mb/d by the year 2010, compared with the reference case. This translates into a loss in annual OPEC oil export revenue of $23 billion. However, this scenario implies exceptionally high tax levels, and it is very likely that alternative options for abatement would be sought.Once full global trading in emissions is allowed, the cost imposed upon carbon‐use falls dramatically, down to $15 per tonne of CO2, bringing OPEC revenue losses down to below $12 bn per annum. There may perhaps be only limited scope for OPEC to defend its oil revenue by adopting a firm price strategy consistent with significant production restraint. However, the idea of joint production restraint with non‐OPEC could lend some plausibility to the idea of using market management to ensure steady oil export revenue that would otherwise be eroded by climate change mitigation policies.
The Future of Gaseous Fuels in Hong Kong
Authors: Chow Larry Chuen‐ho 
Published: March 2003

There are three types of gaseous fuel in Hong Kong. Natural gas, exclusively used for power generation and imported under a 20‐year contract, accounted for 16 per cent of total primary energy requirements in 1998. Towngas, manufactured from naphtha, and liquefied petroleum gas are the two other kinds, accounting for about 9.5 per cent of the final energy requirement in recent years. The first part of this paper analyses the competition between these two gaseous fuels since 1984, elucidating in detail how towngas came to dominate the gaseous fuel market.The government of the Hong Kong Special Administrative Region would like to boost the use of natural gas in Hong Kong, on account of its environmental benefits and cost competitiveness. It is considering the possibility of using natural gas to replace the other two gaseous fuels and adopting the common carrier system, in order to spur competition in the gaseous fuel market. The second part of the study evaluates the feasibility of converting to natural gas and opening up the pipeline system, putting forth a rough schedule for the whole process.
The Development of the Year Curriculum Coordinator at Burntwood School
Authors: Harper Charles , Barry Yvonne 
Published: March 2003

This article gives an account of a school in which Year Curriculum Teams were created, consisting of a planned combination of tutors across subject clusters. An enhanced role and perspective for the tutor is described. Subsequent changes were accommodated well by the new system, even though the position regarding tutor continuity was changed. As with other school accounts in this issue, a sense of the particular flavour of the school comes through, alongside the structural themes which may have wide application.Charles Harper and Yvonne Barry are both members of the Senior Management Team at Burntwood School, which has recently been awarded Beacon status. Charles has taught in a number of schools including in Pennsylvania, USA. He was a Head of Art before moving into senior management. Yvonne has taught in two large comprehensive schools and was a Year Curriculum Coordinator before becoming a senior manager. Both have been involved in training staff and in giving presentations at the Institute of Education, CSCS, QME and various London schools. Charles and Yvonne are members of various working groups and advisory bodies including the Open University and the QCA.
Teachers’ Attitudes towards Disruptive Behaviour and their Use of Internal Referral
Authors: Evans Michael 
Published: March 2003

This study offers a very neat demonstration of something which conventional wisdom holds: that our actions reflect our beliefs. But the topic under investigation is a challenging one – teachers’ uses of ‘referral systems’ in school. The evidence suggests that referrals reflect teachers’ beliefs – not, therefore, the pupils’ behaviour. We do not know of a study of this sort anywhere in the literature on school behaviour, yet these findings have major implications for those pastoral systems which have become distorted into discipline systems. Michael examines these with care, taking pains not to be simply ‘pointing the finger’.Michael Evans has been teaching physical education and mathematics in London for seven years. Currently in his second secondary post as Head of Year, Michael is working to complete his MA at the University of London Institute of Education. In his spare time he heads for the hills, wind and rain of Scotland.
In The Shadow Of The Divine: Negative Theology And Negative Anthropology In Augustine, Pseudo‐Dionysius And Eriugena
Authors: Otten Willemien 
Published: March 2003

This article takes its starting‐point in the current resurgence of interest in negative theology. Being especially prevalent among postmodern thinkers, this interest coincides with a strong conviction concerning the absence of the divine. In the postmodern context the interest in negative theology leads quite naturally into a debate on negative anthropology, as humanity's increasing awareness of its own finitude appears to reflect a similar break with the metaphysics of being.To analyze the tradition of negative theology, the article goes back to its prime architect, Pseudo‐Dionysius (500 C.E). By comparing him to an author who preceded him, viz. Augustine, and one who followed him, viz. Eriugena, the article aims at giving a ‘thicker’ description of his position by framing it historically. In doing so it draws two conclusions. It first shows that the connection between negative theology and negative anthropology is indeed Dionysian; as such it is rightfully pointed to in postmodern thought. In contradistinction to postmodern applications, however, Dionysius' interest in negativity is shown to reflect before all a desire to wrestle with the overpowering presence of the divine instead of concluding to its absence.