bluuebunny/crossref_metadata_2025 huggingface dataset:
A Biomedical Application of Latent Class Models with Random Effects
Authors: Hadgu Alula , Qu Yinsheng
Published: March 2003

Traditional latent class modelling has been used in many biomedical settings. Unfortunately, many of these applications assume that the diagnostic tests are independent given the true disease status, an assumption that is often violated in practice. Qu, Tan and Kutner developed general latent class models with random effects to model the conditional dependence among multiple diagnostic tests. In this paper latent class modelling with random effects is used to estimate the sensitivity and specificity of six screening tests for detecting Chlamydia trachomatis in endocervical specimens from women attending family planning clinics.
The Effect of Non-Stationarity on Extreme Sea-Level Estimation
Authors: Dixon Mark J. , Tawn Jonathan A.
Published: March 2003

The sea-level is the composition of astronomical tidal and meteorological surge processes. It exhibits temporal non-stationarity due to a combination of long-term trend in the mean level, the deterministic tidal component, surge seasonality and interactions between the tide and surge. We assess the effect of these non-stationarities on the estimation of the distribution of extreme sea-levels. This is important for coastal flood assessment as the traditional method of analysis assumes that, once the trend has been removed, extreme sea-levels are from a stationary sequence. We compare the traditional approach with a recently proposed alternative that incorporates the knowledge of the tidal component and its associated interactions, by applying them to 22 UK data sites and through a simulation study. Our main finding is that if the tidal non-stationarity is ignored then a substantial underestimation of extreme sea-levels results for most sites. In contrast, if surge seasonality and the tide–surge interaction are not modelled the traditional approach produces little additional bias. The alternative method is found to perform well but requires substantially more statistical modelling and better data quality.
Design and Analysis of Two-Phase Studies with Binary Outcome Applied to Wilms Tumour Prognosis
Authors: Breslow N. E. , Chatterjee N.
Published: March 2003

Two-phase stratified sampling is used to select subjects for the collection of additional data, e.g. validation data in measurement error problems. Stratification jointly by outcome and covariates, with sampling fractions chosen to achieve approximately equal numbers per stratum at the second phase of sampling, enhances efficiency compared with stratification based on the outcome or covariates alone. Nonparametric maximum likelihood may result in substantially more efficient estimates of logistic regression coefficients than weighted or pseudolikelihood procedures. Software to implement all three procedures is available. We demonstrate the practical importance of these design and analysis principles by an analysis of, and simulations based on, data from the US National Wilms Tumor Study.
Using Orientation Statistics to Investigate Variations in Human Kinematics
Authors: Rancourt Denis , Rivest Louis-Paul , Asselin Jérôm
Published: March 2003

This paper applies orientation statistics to investigate variations in upper limb posture of human subjects drilling at six different locations on a vertical panel. Some of the drilling locations are kinematically equivalent in that the same posture could be used for these locations. Upper limb posture is measured by recording the co-ordinates of four markers attached to the subjects hand, forearm, arm and torso. A 3×3 rotation characterizes the relative orientation of one body segment with respect to another. Replicates are available since each subject drilled at the same location five times. Upper limb postures for the six drilling locations are compared by one-way analysis-of-variance tests for rotations. These tests rely on tangent space approximations at the estimated modal rotation of the sample. A parameterization of rotations in terms of unit quaternions simplifies the computations. The analysis detects significant differences in posture between all pairs of drilling locations. The smallest changes, less than 10° at all joints, are obtained for the kinematically equivalent pairs of locations. A short discussion of the biomechanical interpretation of these findings is presented.
Bias in Meta-Analysis Due to Outcome Variable Selection Within Studies
Authors: Hutton J. L. , Williamson Paula R.
Published: March 2003

Although bias in meta-analysis arising from selective publication has been studied, within-study selection has received little attention. Chronic diseases often have several possible outcome variables. Methods based on the size of the effect allow results from studies with different outcomes to be combined. However, the possibility of selective reporting of outcomes must be considered. The effect of selective reporting on estimates of the size of the effect and significance levels is presented, and sensitivity analyses are suggested. Substantial publication bias could arise from multiple testing of outcomes in a study, followed by selective reporting. Two meta-analyses, on anthelminth therapy and a treatment for incontinence, are reassessed allowing for within-study selection, as it is clear that more outcomes had been measured than were reported. The sensitivity analyses show that the robustness of the anthelminth results is dependent on what assumption one makes about the reporting strategy for the largest trial. The possible influence of correlation between within-child measurements was such that the conclusions could easily be reversed. The effect of a mild assumption on within-trial selection alone could alter general recommendations about the treatment for incontinence.
Bayesian Volumetric Calibration: An Application of Reversible Jump Markov Chain Monte Carlo Methods
Authors: Henderson Robin , Morton-Jones Tony , McKnespiey Paul
Published: March 2003

Volumetric calibration is used for high accuracy estimation of the functional volume-to-level relationship for vessels used to store hazardous liquids. An example of calibration of a vessel for reprocessed nuclear material is used to illustrate an analysis of calibration data. We advocate a Bayesian approach, with proper account of genuine prior information, using a reversible jump Markov chain Monte Carlo method for estimation.
Monitoring Processes with Data Censored Owing to Competing Risks by Using Exponentially Weighted Moving Average Control Charts
Authors: Steiner Stefan H. , MacKay R. Jock
Published: March 2003

In industry, process monitoring is widely employed to detect process changes rapidly. However, in some industrial applications observations are censored. For example, when testing breaking strengths and failure times often a limited stress test is performed. With censored observations, a direct application of traditional monitoring procedures is not appropriate. When the censoring occurs due to competing risks, we propose a control chart based on conditional expected values to detect changes in the mean strength. To protect against possible confounding caused by changes in the mean of the censoring mechanism we also suggest a similar chart to detect changes in the mean censoring level. We provide an example of monitoring bond strength to illustrate the application of this methodology.
Using Auxiliary Data for Parameter Estimation with Non-Ignorably Missing Outcomes
Authors: Ibrahim Joseph G. , Lipsitz Stuart R. , Horton Nick
Published: March 2003

We propose a method for estimating parameters in generalized linear models when the outcome variable is missing for some subjects and the missing data mechanism is non-ignorable. We assume throughout that the covariates are fully observed. One possible method for estimating the parameters is maximum likelihood with a non-ignorable missing data model. However, caution must be used when fitting non-ignorable missing data models because certain parameters may be inestimable for some models. Instead of fitting a non-ignorable model, we propose the use of auxiliary information in a likelihood approach to reduce the bias, without having to specify a non-ignorable model. The method is applied to a mental health study.
Radiocarbon Dating with Temporal Order Constraints
Authors: Nicholls Geoff , Jones Martin
Published: March 2003

Bayesian methods are now widely used for analysing radiocarbon dates. We find that the non-informative priors in use in the literature generate a bias towards wider date ranges which does not in general reflect substantial prior knowledge. We recommend using a prior in which the distribution of the difference between the earliest and latest dates has a uniform distribution. We show how such priors are derived from a simple physical model of the deposition and observation process. We illustrate this in a case-study, examining the effect that various priors have on the reconstructed dates. Bayes factors are used to help to decide model choice problems.
Geoadditive Models
Authors: Kammann E. E. , Wand M. P.
Published: March 2003

A study into geographical variability of reproductive health outcomes (e.g. birth weight) in Upper Cape Cod, Massachusetts, USA, benefits from geostatistical mapping or kriging. However, also observed are some continuous covariates (e.g. maternal age) that exhibit pronounced non-linear relationships with the response variable. To account for such effects properly we merge kriging with additive models to obtain what we call geoadditive models. The merging becomes effortless by expressing both as linear mixed models. The resulting mixed model representation for the geoadditive model allows for fitting and diagnosis using standard methodology and software.
Bayesian Texture Segmentation of Weed and Crop Images Using Reversible Jump Markov Chain Monte Carlo Methods
Authors: Dryden Ian L. , Scarr Mark R. , Taylor Charles C.
Published: March 2003

A Bayesian method for segmenting weed and crop textures is described and implemented. The work forms part of a project to identify weeds and crops in images so that selective crop spraying can be carried out. An image is subdivided into blocks and each block is modelled as a single texture. The number of different textures in the image is assumed unknown. A hierarchical Bayesian procedure is used where the texture labels have a Potts model (colour Ising Markov random field) prior and the pixels within a block are distributed according to a Gaussian Markov random field, with the parameters dependent on the type of texture. We simulate from the posterior distribution by using a reversible jump Metropolis–Hastings algorithm, where the number of different texture components is allowed to vary. The methodology is applied to a simulated image and then we carry out texture segmentation on the weed and crop images that motivated the work.
Diagnostic checking of nonlinear multivariate time series with multivariate arch errors
Authors: Ling Shiqing , Li W. K.
Published: March 2003

Multivariate time series with multivariate ARCH errors have been found useful in many applications. In order to check the adequacy of these models, we define the sum of squared (standardized) residual autocorrelations and derive their asymptotic distribution. The results are used to derive several new multivariate portmanteau tests. Simulation results show that the asymptotic standard errors are quite satisfactory compared with empirical standard errors and that the tests have reasonable empirical size and power. The distribution of the standardized residual autocorrelations is also derived.
Error‐correction Mechanism Tests for Cointegration in a Single‐equation Framework
Authors: Banerjee Anindya , Dolado Juan , Mestre Ricardo
Published: March 2003

A new test is proposed for cointegration in a single‐equation framework where the regressors are weakly exogenous for the parameters of interest. The test is denoted as an error‐correction mechanism (ECM) test and is based upon the ordinary least squares coefficient of the lagged dependent variable in an autoregressive distributed lag model augmented with leads of the regressors. The limit distributions of the standardized coeffi cient and t‐ratio versions of the ECM tests are obtained and critical values are provided. These limit distributions do not depend upon nuisance parameters but they depend on the number of regressors. Finally, we compare their power properties with those of other cointegration tests available in the literature and find the circumstances under which the ECM tests have a better performance.
A Class of Non‐Embeddable ARMA Processes
Authors: Brockwell A. E. , Brockwell P. J.
Published: March 2003

We show that a stationary ARMA(p, q) process {Xn = 0, 1, 2, ...} whose moving‐average polynomial has a root on the unit circle cannot be embedded in any continuous‐time autoregressive moving‐average (ARMA) process {Y}(t), t≥ 0}, i.e. we show that it is impossible to find a continuous‐time ARMA process {Y}(t)} whose autocovariance function at integer lags coincides with that of {Xn}. This provides an answer to the previously unresolved question raised in the papers of Chan and Tong (J. Time Ser. Anal. 8 (1987), 277–81), He and Wang (J. Time Ser. Anal. 10 (1989), 315–23) and Brockwell (J. Time Ser. Anal. 16 (1995), 451–60).
Semiparametric Inference in Seasonal and Cyclical Long Memory Processes
Authors: Arteche Josu , Robinson Peter M.
Published: March 2003

Several semiparametric estimates of the memory parameter in standard long memory time series are now available. They consider only local behaviour of the spectrum near zero frequency, about which the spectrum is symmetric. However long‐range dependence can appear as a spectral pole at any Nyqvist frequency (reflecting seasonal or cyclical long‐memory), where the spectrum need display no such symmetry. We introduce Seasonal/Cyclical Asymmetric Long Memory (SCALM) processes that allow differing rates of increase on either side of such a pole. To estimate the two consequent memory parameters we extend two semiparametric methods that were proposed for the standard case of a spectrum diverging at the origin, namely the log‐periodogram and Gaussian or Whittle methods. We also provide three tests of symmetry. Monte Carlo analysis of finite sample behaviour and an empirical application to UK inflation data are included. Our models and methods allow also for the possibility of negative dependence, described by a possibly asymmetric spectral zero.
Simple Regressions with Linear Time Trends
Authors: Hasseler Uwe
Published: March 2003

Simple regressions of two trend stationary time series are considered. As the linear trend dominates the stochastic components the rates of convergence and the limiting distributions of ordinary least squares statistics are exactly the same as in the case of cointegrated regressions with drifts. In particular, asymptotic standard normal t statistics are readily available. Hence, asymptotic inference requires no distinction between simple regressions of trend stationary series and of cointegrated variables with drifts.
Subset ARMA Model Identification Using Genetic Algorithms
Authors: Gaetan Carlo
Published: March 2003

Subset models are often useful in the analysis of stationary time series. Although subset autoregressive models have received a lot of attention, the same attention has not been given to subset autoregressive moving‐average (ARMA) models, as their identification can be computationally cumbersome. In this paper we propose to overcome this disadvantage by employing a genetic algorithm. After encoding each ARMA model as a binary string, the iterative algorithm attempts to mimic the natural evolution of the population of such strings by allowing strings to reproduce, creating new models that compete for survival in the next population. The success of the proposed procedure is illustrated by showing its efficiency in identifying the true model for simulated data. An application to real data is also considered.
Time Series Models in Non‐Normal Situations: Symmetric Innovations
Authors: Tiku M. L. , Wong Wing‐Keung , Vaughan David C. , Bian Guorui
Published: March 2003

We consider AR(q) models in time series with non‐normal innovations represented by a member of a wide family of symmetric distributions (Student's t). Since the ML (maximum likelihood) estimators are intractable, we derive the MML (modified maximum likelihood) estimators of the parameters and show that they are remarkably efficient. We use these estimators for hypothesis testing, and show that the resulting tests are robust and powerful.
Bootstrap Tests for an Autoregressive Unit Root in the Presence of Weakly Dependent Errors
Authors: Psaradakis Zacharias
Published: March 2003

This paper examines bootstrap tests of the null hypothesis of an autoregressive unit root in models that may include a linear rend and/or an intercept and which are driven by innovations that belong to the class of stationary and invertible linear processes. Our approach makes use of a sieve bootstrap procedure based on residual resampling from autoregressive approximations, the order of which increases with the sample size at a suitable rate. We show that the sieve bootstrap provides asymptotically valid tests of the unit‐root hypothesis and demonstrate the small‐sample effectiveness of the method by means of simulation.
Prediction and nonparametric estimation for time series with heavy tails
Authors: HALL PETER , PENG LIANG , YAO QIWEI
Published: March 2003

Motivated by prediction problems for time series with heavy‐tailed marginal distributions, we consider methods based on `local least absolute deviations' for estimating a regression median from dependent data. Unlike more conventional `local median' methods, which are in effect based on locally fitting a polynomial of degree 0, techniques founded on local least absolute deviations have quadratic bias right up to the boundary of the design interval. Also in contrast to local least‐squares methods based on linear fits, the order of magnitude of variance does not depend on tail‐weight of the error distribution. To make these points clear, we develop theory describing local applications to time series of both least‐squares and least‐absolute‐deviations methods, showing for example that, in the case of heavy‐tailed data, the conventional local‐linear least‐squares estimator suffers from an additional bias term as well as increased variance.
Bayesian analysis of switching ARCH models
Authors: KAUFMANN SYLVIA , FRÜHWIRTH‐SCHNATTER SYLVIA
Published: March 2003

We consider a time series model with autoregressive conditional heteroscedasticity that is subject to changes in regime. The regimes evolve according to a multistate latent Markov switching process with unknown transition probabilities, and it is the constant in the variance process of the innovations that is subject to regime shifts. The joint estimation of the latent process and all model parameters is performed within a Bayesian framework using the method of Markov chain Monte Carlo (MCMC) simulation. We perform model selection with respect to the number of states and the number of autoregressive parameters in the variance process using Bayes factors and model likelihoods. To this aim, the model likelihood is estimated by the method of bridge sampling. The usefulness of the sampler is demonstrated by applying it to the data set previously used byHamilton and Susmel (1994) who investigated models with switching autoregressive conditional heteroscedasticity using maximum likelihood methods. The paper concludes with some issues related to maximum likelihood methods, to classical model selection, and to potential straightforward extensions of the model presented here.
Comparison of unit root tests for time series with level shifts
Authors: LANNE MARKKU , LÜTKEPOHL HELMUT , SAIKKONEN PENTTI
Published: March 2003

Unit root tests are considered for time series which have a level shift at a known point in time. The shift can have a very general nonlinear form, and additional deterministic mean and trend terms are allowed for. Prior to the tests, the deterministic parts and other nuisance parameters of the data generation process are estimated in a first step. Then, the series are adjusted for these terms and unit root tests of the Dickey–Fuller type are applied to the adjusted series. The properties of previously suggested tests of this sort are analysed and modifications are proposed which take into account estimation errors in the nuisance parameters. An important result is that estimation under the null hypothesis is preferable to estimation under local alternatives. This contrasts with results obtained by other authors for time series without level shifts.
Filtering and smoothing of state vector for diffuse state‐space models
Authors: Koopman S. J. , Durbin J.
Published: March 2003

Abstract. This paper presents exact recursions for calculating the mean and mean square error matrix of the state vector given the observations for the multi‐variate linear Gaussian state‐space model in the case where the initial state vector is (partially) diffuse.
Unemployment, Vacancies and Unfair Dismissals
Authors: Brown Sarah , Frick Bernd , Sessions John
Published: March 2003

In most West European economies the annual number of grievance procedures settling individual complaints against unfair dismissals has been increasing since the 1960s. This development has very often been attributed to the enactment of legal regulations restricting the dismissal behaviour of firms. Econometric analyses using data from Germany and Great Britain show that labour market developments, namely the flow into unemployment and the vacancy rate, have a much stronger influence on the cyclical demand for grievance procedures than changes in the “legal infrastructure” of the labour market. Without denying the importance of institutional differences it appears that the individual costs of unemployment (which, ceteris paribus, rise as the flow into unemployment increases and the vacancy rate decreases) are superior predictors of the demand for grievance procedures than institutional changes strengthening or weakening employees' rights.
The Quality of Skill Acquisition in Young Workers' First Job
Authors: Green Francis , Montgomery Scott M.
Published: March 2003

Young workers' experiences of their first job form an important stage in the transition from school to work, and the quality of that experience is likely to have a strong bearing on future chances in the labour market. We provide evidence on a key aspect of that experience, namely, whether the skills acquired during the first job are firm‐specific or in some degree transferable. More than one in six young people acquired only firm‐specific skills in their first substantial job. High levels of prior human capital, short training spells or training leading to qualifications tend to raise, while being in casual or temporary jobs tends to lower, the likelihood that transferable skills are acquired.
The Wages of Sin? Illegal Drug Use and the Labour Market
Authors: MacDonald Ziggy , Pudney Stephen
Published: March 2003

We use data from the British Crime Survey (BCS) to analyse the relationship between illicit drug use and labour market outcomes for a sample of men and women aged 16–25. In using these data we highlight a serious design flaw in the BCS questionnaire structure that presents a serious barrier to statistical modelling of drug use at the individual level. We propose a simple way of overcoming this problem and proceed to estimate a model of occupational attainment jointly determined with unemployment and current drug use, conditional on past drug use. Separating the commonly abused drugs into a ‘hard’ and ‘soft’ category, we find that past hard drug use has a significant positive association with current unemployment, but find no significant association between past hard or soft drug use and occupational attainment. We also find no significant association between current drug use and attainment, although we observe that current drug use is associated with current unemployment.
Input and SLA: Adults' Sensitivity to Different Sorts of Cues to French Gender
Authors: Carroll Susanne E.
Published: March 2003

This article investigates experimentally if beginner adult learners, given auditory stimuli, are equally likely to represent French gender subclasses in terms of phonological, morphosyntactic, and/or semantic representations. Eighty‐eight adult English speakers learned patterned [Det + N]French+ translation equivalentEnglish lists. Analyses of results reveal that participants more readily cognized “natural” semantic and morphological patterns; these same lists lent themselves to generalization. The results demonstrate that for this group of learners, the construct of input for gender learning emerges through the construction of abstract knowledge representations, apparently on the basis of prior knowledge, and not solely from objective patterns in the speech signal. They provide support for theories of linguistic cognition involving mediating structural representations, as well as learning theories in which conceptual information can guide grammatical development.
Learner Uptake in Communicative ESL Lessons
Authors: Ellis Rod , Basturkmen Helen , Loewen Shawn
Published: March 2003

This article examines incidental and transitory focus on form. Learner uptake was studied in focus‐on‐form episodes occurring in 12 hours of communicative ESL teaching. Learner uptake was generally high and successful—to a much greater extent than has been reported for immersion classrooms. Uptake was higher and more successful in reactive focus on form and in student‐initiated focus on form than in teacher‐initiated focus on form. The level of uptake was also influenced by whether meaning or form was negotiated and by the complexity of an episode. This study indicates that focus on form can occur without disturbing the communicative flow of a classroom and that the classroom context can affect the amount of uptake.
Patterns of Interaction in ESL Pair Work
Authors: Storch Neomy
Published: March 2003

This study investigated the nature of dyadic interaction in an adult ESL classroom. The study was longitudinal, classroom based, and examined the nature of interaction between 10 pairs of adult ESL students over a range of language tasks and over time (a semester). Four distinct patterns of dyadic interaction were found. These patterns are distinguishable in terms of equality and mutuality (Damon & Phelps, 1989). More importantly, the findings suggest that certain patterns of dyadic interaction are more conducive than others to language learning. These findings are explained by reference to Vygotsky’s theory of cognitive development.
Investigating the Relationship Between Vocabulary Knowledge and Academic Reading Performance: An Assessment Perspective
Authors: Qian David D.
Published: March 2003

The present study was conducted in the context of Test of English as a Foreign Language (TOEFL) 2000 research to conceptually validate the roles of breadth and depth of vocabulary knowledge in reading comprehension in academic settings and to empirically evaluate a test measuring three elements of the depth dimension of vocabulary knowledge, namely, synonymy, polysemy, and collocation. A vocabulary size measure and a TOEFL vocabulary measure were also tested. The study found that the dimension of vocabulary depth is as important as that of vocabulary size in predicting performance on academic reading and that scores on the three vocabulary measures tested are similarly useful in predicting performance on the reading comprehension measure used as the criterion. The study confirms the importance of the vocabulary factor in reading assessment.
“It’s Darwinism – Survival of the Fittest:” How Markets and Reputations Shape the Ways in Which Plaintiffs’ Lawyers Obtain Clients
Authors: Daniels Stephen , Martin Joanne
Published: March 2003

The survival of a plaintiffs’ lawyer’s practice depends upon the generation of an ongoing flow of clients with injuries that the civil justice system will compensate adequately. If this requirement is not met, lawyers will leave this aspect of the legal market for more promising ones. If they do, legal services for injured people will be diminished as a result. In order to find out how this personal services legal market is defined and developed, we interviewed ninety‐five plaintiffs’ lawyers in Texas. These lawyers use four major strategies to get clients: client referrals, lawyer referrals, direct marketing, and other referrals. What any particular lawyer does is shaped by the geographic market from which clients are drawn, and by the lawyer’s reputation. Our findings provide fresh insights for the empirical literature on plaintiffs’ lawyers, and they provide an empirical context for assessing the potential impact of changes in the civil justice system, like tort reform, on the ability of plaintiffs’ lawyers to obtain clients.
Introduction: Comparing National Styles of Regulation in Japan and the United States
Authors: Kagan Robert
Published: March 2003

The articles in this issue generally reinforce conventional images of American regulation as often adversarial and legalistic and of Japanese regulation as more informal and cooperative. They also suggest that, in regulating pollution and occupational safety in larger firms, Japan’s regulatory style is equally effective and more economically efficient than the American approach. But Japan’s style appears less effective when regulation requires changes in elite attitudes, as in the realm of workplace equality for women. Moreover, developments in Japan’s financial sector reveal ways in which informal regulation can result in undue deference to business and political interests.
Introduction: Problem‐Solving Courts
Authors: Butts Jeffrey
Published: March 2003

Problem‐solving courts have become a significant feature of the U.S. justice system, and their popularity appears to be growing internationally with courts under way or in development in countries such as Australia and Great Britain. Drug courts are the most visible type of problem‐solving court, but other varieties are beginning to take hold. Mental health courts, domestic violence courts, and community‐based courts among others are beginning to handle a considerable portion of the legal workload in many jurisdictions. Criminal law violations as well as neighborhood conflicts and interpersonal disputes are increasingly being referred to problem‐solving courts rather than to traditional criminal or civil courts.
Assessing the Costs and Benefits Accruing to the Public from a Graduated Sanctions Program for Drug‐Using Defendants
Authors: Roman John , Harrell Adele
Published: March 2003

This paper presents a cost‐benefit analysis of the returns to the public from reductions in recidivism associated with a graduated sanctioning program for drug felony defendants. Estimates of program costs for operating a court‐based drug testing and sanctioning program are presented with estimates of the value of potential benefits of averted criminal incidents and crime control. The results, based on the evaluation of the Superior Court Drug Intervention Program in Washington, D.C., found that the program saved two dollars in averted crime‐related costs for every dollar spent on the program. This paper presents explicit description of the methods used to derive these results so that they may be applied to the evaluation of other experimental/quasi‐experimental programs.
The Politics of Adoption: Child Rights in the Brazilian Setting
Authors: Fonseca Claudia
Published: March 2003

This paper, centered on adoption policy in Brazil, asks to what extent the open–ended principles apparent in international child rights accords, filtered down through different national laws, adjust to local realities. Ethnographic data on child circulation practices in urban favelas is compared with specific clauses in the 1990 Brazilian Children’s Code, as well as with adoption policies in North America, to question the code’s way of legislating which children can be placed for adoption, on what terms they should be placed, and who has the power to place them.
The Timing of New Technology Adoption: Theoretical Models and Empirical Evidence
Authors: Hoppe Heidrun C.
Published: March 2003

This paper surveys the theoretical literature on the timing of new technology adoption. It presents the state of the art as it falls into two major categories, depending on whether the particular model deals with uncertainty regarding the arrival and value of a new technology and/or strategic interaction in the product market. Empirical evidence is reviewed, and recommendations are given for future research.
The Determinants of Technology Diffusion: Evidence from the UK Financial Sector
Authors: Gourlay Adrian , Pentecost Eric
Published: March 2003

We investigate the role of firm‐ and industry‐specific factors in the diffusion of automated teller machines in the UK financial sector. A duration model of technology adoption is employed in the empirical modelling and is applied to an annual panel of adoption histories over the period 1972–97. The main factors affecting the diffusion of new technology are found to be endogenous learning, cumulative learning‐by‐doing effects, firm size, growth and profitability, and price expectations. There is little evidence, however, to support the role of stock effects in the diffusion process. The results are found to be robust across a number of specifications of the baseline hazard function.
‘Footloose’ Multinationals?
Authors: Görg Holger , Strobl Eric
Published: March 2003

We examine whether multinational companies are more footloose than their domestic counterparts in the host country, using data for the Irish manufacturing sector. First, we investigate whether plant survival rates differ between multinationals and indigenous plants. Second, we analyse whether employment is more unstable inmultinationals. As regards the first aspect we find that multinationals are morelikely to exit the market than indigenous plants when we control for other plant–and industry–specific characteristics. In terms of employment persistence we find that new jobs generated in multinational companies appear to be more persistent than jobs generated in indigenous plants. In contrast, they are not any more or less likely to reverse employment reductions, all other things being equal.
The Backward–Bending Phillips Curve And The Minimum Unemployment Rate Of Inflation: Wage Adjustment With Opportunistic Firms
Authors: Palley Thomas I.
Published: March 2003

This paper presents a theory of the backward–bending Phillips curve. There is aminimum unemployment rate of inflation which offers a policy alternative to the non–accelerating inflation rate of unemployment. Nominal wages are downwardly rigid because workers oppose cuts initiated from within the employment relation. Instead, workers may acceptreal wage adjustments effected by increases in the general price level, a variableoutside individual firms’ control. This is why inflation ‘greases’labor market adjustment. However, workers resist too rapid a real wage adjustment,and too high an inflation generates wage resistance that cancels the grease effect and increases unemployment.
Saving Behaviour in OECD Countries: Evidence from Panel Cointegration Tests
Authors: Sarantis Nicholas , Stewart Chris
Published: March 2003

We use recently developed panel cointegration and integration tests, which allow for heterogeneity in parameters and dynamics across countries, to examine the long‐run determinants of aggregate private saving rates in a dynamic panel of OECD countries during the post Second World War period. These techniques are more powerful than the conventional tests and overcome the inconsistency problem of the fixed‐effect estimator typically employed in cross‐country studies of saving behaviour. We employ a number of alternative cointegration methods and also construct a private disposable income series, while previous studies on private savings tend to proxy income with GDP. We find strong evidence for the existence of a long‐run equilibrium saving function based on an extended version of the life‐cycle hypothesis which allows for the influence of liquidity constraints. Our results suggest a number of significant determinants of saving rates, but the parameter estimates vary significantly across countries.
Explaining Stock Market Correlation: A Gravity Model Approach
Authors: Flavin Thomas J , Hurley Margaret J , Rousseau Fabrice
Published: March 2003

A gravity model, frequently used to explain trade patterns, is used to explain stock market correlations. The main result of the trade literature is that geography matters for goods markets. Physical location and trading costs should be less of an issue in asset markets. However, we find that geographical variables still matter when examining equity market linkages. In particular, the number of overlapping opening hours and sharing a common border tends to increase cross–country stock market correlation. These results may stem from asymmetrical information and investor sentiment, lending some empirical support for these explanations of the international diversification puzzle.
Arbitrage and Growth Rate for Riskless Investments in a Stationary Economy
Authors: Adler Ilan , Gale David
Published: March 2003

A sequential investment is a vector of payments over time, (a0, a1, ... ,an), where a payment is made to or by the investor according as ai is positive or negative. Given a collection of such investments it may be possible to assemble a portfolio from which an investor can get “something for nothing,” meaning that without investing any money of his own he can receive a positive return after some finite number of time periods. Cantor and Lipmann (1995) have given a simple necessary and sufficient condition for a set of investments to have this property. We present a short proof of this result. If arbitrage is not possible, our result leads to a simple derivation of the expression for the long–run growth rate of the set of investments in terms of its “internal rate of return.”
Time Changes for Lévy Processes
Authors: Geman Hélyette , Madan Dilip B. , Yor Marc
Published: March 2003

The goal of this paper is to consider pure jump Lévy processes of finite variation with an infinite arrival rate of jumps as models for the logarithm of asset prices. These processes may be written as time‐changed Brownian motion. We exhibit the explicit time change for each of a wide class of Lévy processes and show that the time change is a weighted price move measure of time. Additionally, we present a number of Lévy processes that are analytically tractable, in their characteristic functions and Lévy densities, and hence are relevant for option pricing.
A Note on the Boyle–Vorst Discrete‐Time Option Pricing Model with Transactions Costs
Authors: Palmer Ken
Published: March 2003

Working in a binomial framework, Boyle and Vorst (1992) derived self‐financing strategies perfectly replicating the final payoffs to long positions in European call and put options, assuming proportional transactions costs on trades in the stocks. The initial cost of such a strategy yields, by an arbitrage argument, an upper bound for the option price. A lower bound for the option price is obtained by replicating a short position. However, for short positions, Boyle and Vorst had to impose three additional conditions. Our aim in this paper is to remove Boyle and Vorst's conditions for the replication of short calls and puts.
Risking Philosophy of Education
Authors: Weston Anthony
Published: March 2003

Teaching philosophy of education offers us a chance to apply the familiar Socratic dialectic to ourselves. But it is very seldom taught in this spirit, if taught at all. Perhaps we fear that such a course would be impossibly self‐referential. This paper argues, however, that precisely this kind of self‐reference could be its strength. I outline a course of this sort, based upon a number of iterations I have taught over the past few years. A range of different classroom styles are enacted and examined for their hidden assumptions about teaching, learning, and knowledge.
Conventions and Rules in Literature
Authors: Olsen Stein Haugom
Published: March 2003

Views of what role convention plays in the creation and appreciation of art works gravitate towards two extremes. One view holds that works of art can be apprehended and appreciated as well as created with no reference to convention. The other claims that conventions fully determine how works of art are apprehended and are therefore necessary conditions for the creation of works of art as well as constitutive of appreciation. The former is a version of the Romantic view of art as something that appeals spontaneously to man's most profound emotions, to man's sentient nature, without making use of or needing mediating conventions. The conventionalist view denies that it is possible to respond spontaneously to art. All apprehension and appreciation of art are structured by conventions, and the reader/audience cannot go beyond these conventions because they constitute , the experience of the work of art. This paper explains the sense in which the constitutive view may be best understood.
Priorities of Global Justice
Authors: Pogge Thomas
Published: March 2003

One‐third of all human deaths are due to poverty‐related causes, to malnutrition and to diseases that can be prevented or cured cheaply. Yet our politicians, academics, and mass media show little concern for how such poverty might be reduced. They are more interested in possible military interventions to stop human rights violations in developing countries, even though such interventions – at best – produce smaller benefits at greater cost. This Western priority may be rooted in self‐interest. But it engenders, and is sustained by, a deeply flawed moral presentation of global economic cooperation. The new global economic order we impose aggravates global inequality and reproduces severe poverty on a massive scale. On any plausible understanding of our moral values, the prevention of such poverty is our foremost responsibility.
Towards a Critical Theory of Transnational Justice
Authors: Forst Rainer
Published: March 2003

This paper argues for a conception of transnational justice that provides an alternative to globalist and statist views. In light of an analysis of the transnational context of justice, a critical theory is suggested that addresses the multiple relations of injustice and domination to be found in this context. Based on a universal, individual right to reciprocal and general justification, this theory argues for justifiable social and political relations both within and between states. In both of these contexts, it distinguishes between minimal and maximal justice and stresses the interdependence of domestic and transnational justice. On both levels, minimal justice calls for a discursive structure of justification, whereas maximal justice implies a fully justified basic social structure.
Increasing Returns and Intensification: A Reprise on Ester Boserup's Model of Agricultural Growth
Authors: Winfrey William , Darity Jr William
Published: March 2003

The dynamics of Ester Boserup's model of intensification of ``primitive'' (non‐chemical, non‐mechanized) agriculture have been worked out in three papers by Darity, Pryor and Maurer, and Salehi‐Isfahani under conditions where techniques generating higher levels of food production require longer hours of work. But Boserup's theory suggests that continued intensification can lead to productivity increases in food production. Here the long run implications for agricultural productivity are explored when increasing returns evolve from Boserup's intensification process. Variations in the dynamics of a Boserupian economy are considered under different patterns of response to falling incomes and changing work requirements.
Predator–Prey Model Estimates of the Cyclical Profit Squeeze
Authors: Goldstein Jonathan P.
Published: March 2003

This paper extends the empirical literature on the cyclical profit squeeze (CPS) theory of crisis by developing a multivariate model with superior decomposition methods. A structural time series (unobserved components) model with trend and structural VAR components is employed. The VAR captures the dynamic cyclical interaction between unemployment and profit's share of income and is interpreted as a linear version of Goodwin's (1967) predator‐prey model. Model extensions incorporate the accumulation process and structural shifts. Estimation results for the US economy are used to sort out the controversial relevance of the CPS in the post‐1970 period. It is concluded that the CPS is relevant during the period from 1949 to 1985, but is moderately weakened in the post‐1970 period. Inconclusive statistical support for the CPS is found for the post‐1985 era.
Endogenous Money: What it is and Why it Matters
Authors: Palley Thomas I.
Published: March 2003

Endogenous money is widespread in economic theory. The post‐Keynesian contribution is identification of a causal link between bank lending and the money supply. Though driven by macroeconomic concerns, the post‐Keynesian debate has reduced to a microeconomic debate over the role of financial intermediaries in the accommodation process. In the IS–LM model endogenous money flattens the LM. This misses its substantive significance which is the discrediting of monetarist money supply policy rules and monetarist critiques of central banking, its identification of the key role of credit, and its provision of a credit‐driven theory of the business cycle.
Extending Life: Scientific Prospects and Political Obstacles
Authors: Miller Richard A.
Published: March 2003

In the last two decades, biogerontologists have found that the pace of aging can be decelerated in mammals by dietary or genetic means. Though still largely unappreciated by the lay and scientific public alike, these discoveries belie the common assumption that human aging probably cannot be slowed and prompt the question of whether we can use our growing knowledge about aging to produce 90‐year‐old adults who are as healthy and active as today's 50‐year‐olds. This article explores three related issues: first, why discussions of antiaging medicines are no longer silly; next, why the development of antiaging strategies is making so little headway; and last, whether further work in this area would be worthwhile.

By “aging” I mean a process that converts healthy young adults into less healthy older ones with an increasing risk of illness and death. This definition, which seems fairly innocuous, is careful enough to be controversial, because there are many interesting areas of investigation—studies of childhood development; specific late‐life diseases; death or proliferative ennui of cells in culture; leaf abscission; and time‐dependent changes in the chemical composition of wines, cheeses, and bones—that are sometimes proposed in various combinations as worthy of gerontological attention and governmental funding.