bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of change in the presence of informative censoring: application to a longitudinal clinical trial of progressive renal disease
Authors: Schluchter Mark D. , Greene Tom , Beck Gerald J. 
Published: August 2002

AbstractThe rate of change in a continuous variable, measured serially over time, is often used as an outcome in longitudinal studies or clinical trials. When patients terminate the study before the scheduled end of the study, there is a potential for bias in estimation of rate of change using standard methods which ignore the missing data mechanism. These methods include the use of unweighted generalized estimating equations methods and likelihood‐based methods assuming an ignorable missing data mechanism. We present a model for analysis of informatively censored data, based on an extension of the two‐stage linear random effects model, where each subject's random intercept and slope are allowed to be associated with an underlying time to event. The joint distribution of the continuous responses and the time‐to‐event variable are then estimated via maximum likelihood using the EM algorithm, and using the bootstrap to calculate standard errors. We illustrate this methodology and compare it to simpler approaches and usual maximum likelihood using data from a multi‐centre study of the effects of diet and blood pressure control on progression of renal disease, the Modification of Diet in Renal Disease (MDRD) Study. Sensitivity analyses and simulations are used to evaluate the performance of this methodology in the context of the MDRD data, under various scenarios where the drop‐out mechanism is ignorable as well as non‐ignorable. Copyright © 2001 John Wiley & Sons, Ltd.
Revision of the ICIDH Severity of Disabilities Scale by data linking and item response theory
Authors: van Buuren S. , Hopman‐Rock M. 
Published: August 2002

AbstractThe Severity of Disabilities Scale (SDS) of the ICIDH reflects the degree to which an individual's ability to perform a certain activity is restricted. This paper describes the application of two models from item response theory (IRT), the graded response model and the partial credit model, in order to derive a tentative proposal for a revised SDS. The key ingredient of the approach is to scale existing disability items obtained in different studies on a common scale by exploiting the overlap. Both IRT models are fitted to a linked data set containing items for measuring walking disability. Based on these solutions, a tentative SDS is constructed. The paper concludes with a discussion of the implications, limitations and advantages of the approach. Copyright © 2001 John Wiley & Sons, Ltd.
Logistic discrimination of mixtures of M. tuberculosis and non‐specific tuberculin reactions
Authors: Nagelkerke Nico J. D. , Borgdorff Martien W. , Kim Sang Jae 
Published: August 2002

AbstractInterpretation of the Mantoux test for tuberculous infection can be complicated by cross‐reactions caused by infection with non‐specific mycobacteria. Thus, the distribution of positive indurations is a mixture of two distributions. To estimate tuberculous infection prevalence, the marginal distribution of indurations needs to be separated into its component distributions. Observations from several populations with different mixes of the two types of infection are required. Homogeneity across populations of distributions of indurations for each type of infection is assumed. A logistic model is specified for the probability of having tuberculous infection conditional on the observed induration size. No other assumptions about the two distributions are made. Maximum likelihood is used to estimate the logistic function. Goodness‐of‐fit criteria are discussed. The method is applied to a series of tuberculin surveys carried out in (South) Korea. Estimated infection prevalence agrees reasonably well with severalad hoccriteria. The goodness‐of‐fit test rejects underlying assumptions of homogeneity. One reason appears to be a decline over time in induration sizes caused by tuberculous infection. However, not all reasons for this rejection are obvious. The proposed method of mixture analysis provides an additional tool for the interpretation of prevalence survey data where the diagnostic test lacks specificity as a result of cross‐reactions. Copyright © 2001 John Wiley & Sons, Ltd.
Important ECG diagnosis‐aiding indices of ventricular septal defect children with or without congestive heart failure
Authors: Guo Meihui , Huang Mong‐Na Lo , Bai Zhidong , Hsieh Kai‐Sheng 
Published: August 2002

AbstractIn this paper we perform a statistical study of the conventional RR intervals and two newly defined PR′ and RT intervals of ECG data. A quadratic classification rule is applied to extract several important ECG diagnosis‐aiding indices among normal children and children with ventricular septal defect (VSD) with or without congestive heart failure (CHF). The results show that certain statistics computed from PR′, RR and RT intervals are important diagnosis‐aiding indices. Best classification vectors are searched for pairwise classification. Two methods, minimum distance criterion and a two‐stage classification procedure, are considered for three‐way classification. Furthermore, logistic regression models based on transformations of these important diagnosis‐aiding indices are proposed. The receiver operating characteristic curves of the proposed models show better performance than those of linear and quadratic logistic models. In order to proceed with this study, a computer algorithm to automatically detect the three intervals is developed and the related ECG data are collected and analysed. The algorithm is also enhanced with an outlier detection procedure for the automatic measurements of the PR′ and RT intervals. Copyright © 2001 John Wiley & Sons, Ltd.
Modification of pharmacokinetic sampling schedules in clinical phase I trials: a use of Kullback–Leibler information
Authors: Yafune Akifumi , Ishiguro Makio 
Published: August 2002

AbstractIn clinical phase I trials, pharmacokinetic sampling schedules often have to be modified while the trials proceed. The modifications are based on the observations from a limited number of subjects or only one subject in extreme cases. This paper describes a Kullback–Leibler information approach for modifying pharmacokinetic sampling schedules in clinical phase I trials. The proposed approach presupposes that the pharmacokinetic profile for each subject is specified by an appropriate pharmacokinetic model and the subject‐specific parameters. The best modification plan is selected from arbitrarily chosen candidates based on the Kullback–Leibler information. Applications are given to a simulation study and an actual phase I trial of an anti‐cancer drug. Copyright © 2001 John Wiley & Sons, Ltd.
Joint testing of mortality and a non‐fatal outcome in clinical trials
Authors: McMahon Robert P. , Harrell Frank E. 
Published: August 2002

AbstractThe following procedures are proposed for clinical trials of potentially lethal diseases with a non‐fatal primary outcome: (i) comparison of treatments on worst‐rank scores combining mortality and the non‐fatal outcome; (ii) testing first for mortality differences, and then for differences on the worst‐rank scoring if there is no significant evidence for mortality differences. Power and control of type I error rate while testing mortality and worst‐rank scores by Bonferroni or closed testing procedures are compared. Used together these procedures improve power to detect treatments with favourable effects on both mortality and the designated non‐fatal outcome, while reducing the likelihood of declaring that a treatment benefits patients when undetected adverse effects on mortality are present. Copyright © 2001 John Wiley & Sons, Ltd.
Event history graphs for censored survival data
Authors: Dubin Joel A. , Müller Hans‐Georg , Wang Jane‐Ling 
Published: August 2002

AbstractA compact graphical device for combining survival and time‐varying covariate information is proposed. The proposed graph contains the Kaplan–Meier estimator for right‐censored data and a simultaneous display of the behaviour of time‐dependent covariate(s) and the lifetime for each subject in the sample. The observed levels of time‐dependent covariates are possibly subjected to an initial dimension reduction or smoothing step to produce a continuous covariate function. Values of this function are plotted on a horizontal bar for the length of the lifetime of the subject. Covariate information for censored data is also incorporated. The union of the horizontal bars forms the Kaplan–Meier estimator of the survival function. Our graphical method is implemented with a new S‐plus function and demonstrated in several applications. Copyright © 2001 John Wiley & Sons, Ltd.
Estimation of non‐parametric multivariate risk functions in matched case‐control studies with application to the assessment of interactions of risk factors in the study of cancer
Authors: van der Linde Angelika , Osius Gerhard 
Published: August 2002

AbstractIn epidemiological studies one is interested in investigating the probability of disease depending on risk factors and in particular in detecting interactions of risk factors. Within the setting of parametric logistic regression, interactions can be modelled only in a clumsy and limited way. Modelling the risk function non‐parametrically, estimating it, for example, by a smoothing (thin plate) spline is attractive as a more explorative approach. For prospective studies this amounts to smoothing within the framework and distributional assumptions of generalized regression models (for binary observations). Case‐control studies as retrospective studies with exposure to risk factors being observed do not immediately fit into this setting. In the special case of one‐to‐one matched studies, however, there is an appropriate likelihood again within the range of generalized models. Inferences will be illustrated using simulated and real data. Copyright © 2001 John Wiley & Sons, Ltd.
A scheme for a dose‐escalation study when the event is lagged
Authors: Hüsing Johannes , Sauerwein Wolfgang , Hideghéty Katalin , Jöckel Karl‐Heinz 
Published: August 2002

AbstractClassical designs for clinical phase I trials assume that information about a dose‐limiting event (DLE) is available for all the included patients, or advise not to treat new patients until the information is present. If a DLE occurs after a lag, however, information at the current time might not be sufficient to make clear‐cut decisions according to these designs. In particular, if new patients are available, it is not clear whether to include them in the trial. We suggest a rule that decides on the accrual of each individual eligible patient. Simulation studies are presented that indicate an advantage over the standard ‘three‐at‐once’ design in the length of the study. Copyright © 2001 John Wiley & Sons, Ltd.
A local likelihood proportional hazards model for interval censored data
Authors: Betensky Rebecca A. , Lindsey Jane C. , Ryan Louise M. , Wand M. P. 
Published: August 2002

AbstractWe discuss the use of local likelihood methods to fit proportional hazards regression models to right and interval censored data. The assumed model allows for an arbitrary, smoothed baseline hazard on which a vector of covariates operates in a proportional manner, and thus produces an interpretable baseline hazard function along with estimates of global covariate effects. For estimation, we extend the modified EM algorithm suggested by Betensky, Lindsey, Ryan and Wand. We illustrate the method with data on times to deterioration of breast cosmeses and HIV‐1 infection rates among haemophiliacs. Copyright © 2002 John Wiley & Sons, Ltd.
Reproducibility of cardiovascular responses to mental and static tasks
Authors: Seibt Reingard , Scheuch Klaus , Hinz Andreas 
Published: August 2002

AbstractTemporal stability and transsituational consistency are important characteristics of cardiovascular responses to mental or static load. While in the literature stability is generally estimated as the relationship between only two test sessions, it is unknown whether these stability estimates can be generalized across multiple replications of the test situations. Forty subjects (20 males and 20 females) were tested four times with intervals of 1 day, 1 week, and 1 month. Each test session comprised two mental tasks (mental arithmetic and colour–word test) and a static (fingergrip) task. The physiological variables recorded were heart rate, systolic blood pressure, and diastolic blood pressure. The adaptation processes in the course of the four test sessions are more pronounced for the mental tests than for the static test. The temporal stability, restricted to test sessions 1 and 2, can be used to estimate the general stability across all pairs of test sessions. However, there are some non‐systematic differences which indicate that more than two test sessions yield more reliable results. Averaging across two test sessions, compared with the stability of single test sessions, increases the stability of heart rate reactivity from 0.60 to 0.73. Low correlations between the responses to mental and static load indicate that there are different underlying regulatory mechanisms. The results show that the responsivity can be assessed more reliably when more than two tests are performed. The responses to one type of stressors (mental or static) cannot be generalized to an overall responsivity. Copyright © 2001 John Wiley & Sons, Ltd.
Effect of public speaking on gastric myoelectrical reactivity and parasympathetic cardiac control
Authors: Codispoti Maurizio , Mazzetti Michela , Baldaro Bruno , Tuozzi Giovanni , Trombini Giancarlo 
Published: August 2002

AbstractGastrointestinal reactivity is a central concept in several psychosomatic approaches to peptic ulcer disease and irritable bowel disease. One potential limitation of many laboratory studies of gastrointestinal reactivity is their reliance on non‐ecological tasks lacking components of social stressors which may better relate to day to day stress. Otherwise, the public speaking task is a well known stressful procedure and has a high degree of ecological validity. Stress reactions induced by preparation for public speaking are the result of both the cognitive demand of preparing a speech and social anxiety. The aim of this study was to observe the effect of the public speaking test on the electrogastric activity and the relationship between gastric myoelectrical activity and cardiac activity prior to and after the task. In particular, we hypothesized that public speaking would reduce the amplitude of the normal 3 c.p.m. band and that this decrease would be positively correlated with a reduction in respiratory sinus arrhythmia. As expected, the anticipation of public speaking triggered a decrease in respiratory sinus arrhythmia, an increase in heart rate, and higher skin conductance level compared to baseline. On the other hand, our measure of gastric myoelectrical activity was not affected by the public speaking task. Copyright © 2001 John Wiley & Sons, Ltd.
Self‐esteem, personality and post traumatic stress symptoms following the dissolution of a dating relationship
Authors: Chung Man Cheung , Farmer Steven , Grant Keren , Newton Rebecca , Payne Sally , Perry Melissa , Saunders Jenny , Smith Charlotte , Stone Nina 
Published: August 2002

AbstractThe present study aimed to ascertain the extent to which people, following the dissolution of a dating relationship, experienced post traumatic stress symptoms. It also aimed to investigate the relationship between post traumatic stress and self‐esteem and personality. The hypotheses were that there would be a severe degree of post traumatic stress symptoms experienced by the present samples, and that the personality factor, in particular, neuroticism, and low self‐esteem would be associated with the samples' post traumatic stress symptoms. Sixty heterosexual subjects who had experienced a romantic relationship dissolution over the past 24 months were recruited for the study. They were interviewed with the Impact of Event Scale (IES), the General Health Questionnaire‐28 (GHQ‐28), the Self‐Esteem Rating Scale (SERS) and the Eysenck Personality Questionnaire‐R Short Scale (EPQ‐R). The results showed that 72 per cent of the subjects scored at or above the high IES symptom cut‐off. Forty‐three per cent scored above the cut‐off of the GHQ‐28. Significant correlations were found between the impact of the dissolution and general health. The present subjects were significantly less extroverted and neurotic than the standardized samples. Stepwise regression analyses showed that negative self‐esteem significantly predicted avoidance and the total general health, and that neuroticism significantly predicted the total impact of the dissolution. Copyright © 2002 John Wiley & Sons, Ltd.
Competitive strategies of religious organizations
Authors: Miller Kent D. 
Published: August 2002

AbstractIn recent years, sociologists and economists have given increased attention to studying religious organizations. Their writings raise unresolved issues related to topics within strategic management. This study brings theoretical perspectives from strategic management together with those of sociology and economics to understand the organizational and competitive aspects of religion. The initial portion of this article examines the nature of religious production, competition, and organization. Subsequent sections elaborate specific strategic management issues arising in religious organizations. Resource‐based and institutional perspectives provide a foundation for analyzing the sources of sustainable competitive advantage among religious organizations. The latter portion of this article shifts to the industry level of analysis and examines the roles of political strategies and strategic alliances in shaping religious competition. This theoretical discussion generates testable propositions regarding the competitive strategies of religious organizations and opens opportunities for future research. Copyright © 2002 John Wiley & Sons, Ltd.
Piecemeal legacy migrating with an architectural pattern language: a case study
Authors: Goedicke M. , Zdun U. 
Published: August 2002

AbstractNumerous large applications that have evolved over many years are well‐functioning and reliable, but have severe problems regarding flexibility and reuse. Due to the many fixes that were applied in a system's lifetime, it is often hard to customize, change or exchange system parts. Therefore, it is problematic to migrate such systems to a more flexible architecture or to new technologies. The document archive/retrieval system, discussed in this article, is an example of a large C system that had such problems. As a solution, we will sketch an architectural pattern language that involves patterns well‐suited for a piecemeal migration process. The patterns aim at building and composing highly flexible black‐box component architectures with an object‐oriented glueing layer. We present a re‐engineering case study for the document archive/retrieval system based on these patterns. The patterns are used to wrap the existing C implementations and integrate them with an object system. Moreover, the patterns introduce flexibility hooks into the hot spots of the architecture and let components define their required environment. This enables an easier future evolution of the system. The case study demonstrates a pattern language as an approach for piecemeal legacy migration apart from implementation details. Copyright © 2002 John Wiley & Sons, Ltd.
Schrödinger's token
Authors: Aycock John , Horspool R. Nigel 
Published: August 2002

AbstractA common problem when writing compilers for programming languages or little, domain‐specific languages is that an input token may have several interpretations, depending on context. Solutions to this problem demand programmer intervention, obfuscate the language's grammar, and may introduce subtle bugs. We present a technique which is simple and without the above drawbacks—allowing a token to simultaneously have different types—and show how it can be applied to areas such as little language processing and fuzzy parsing. We also describe ways that compiler tools can support this technique. Copyright © 2001 John Wiley & Sons, Ltd.
Maturing experience base concepts at DaimlerChrysler
Authors: Schneider Kurt , Schwinn Thilo 
Published: August 2002

AbstractBasili coined the term ‘Experience Factory’ for a separate unit in a software company; it helps to exchange experiences between projects. The persistent storage device of such an Experience Factory was called the Experience Base. At DaimlerChrysler, we started in 1997 to establish local ‘Software Experience Centers’, a similar role to an Experience Factory. From the beginning, one of our focal aspects was the design and implementation of an adequate Experience Base. We expected an easy win. However, developing an effective Experience Base turned out to be one of the more difficult tasks. We had to go through several steps of substantial redesign before we achieved a concept of Experience Bases that does now suit our needs. In this paper we describe the most important insights, show examples of their impact on our Experience Base concepts, and discuss modifications made. As a conclusion, we present an evaluation sheet for Experience Base maturity profiles. Copyright © 2001 John Wiley & Sons, Ltd.
Turning development standards into repositories of experiences
Authors: Henninger Scott 
Published: August 2002

AbstractThere has been a resurgence of interest in developing organization‐wide standard development methodologies (SDMs) for software development. It is well known that creating an SDM is only the first step in the process of improving software engineering practices in an organization. SDMs must become living documents that evolve with changing software development needs. The research presented in this paper presents a tool and associated methodology that helps organizations tailor SDMs to the individual needs of projects and capture project experiences that are used to refine and modify the standard. In addition to creating a flexible software process with necessary degrees of formal procedures to ensure high‐quality products, a secondary goal of this research is to turn SDMs into a resource for software managers and developers, something that truly supports the development process as it is actually practised. This approach features a methodology based on organizational learning principles, a rule‐based system to tailor the SDM to meet the characteristics of individual projects, and a case‐based architecture to capture and provide relevant development knowledge throughout the development lifecycle. Copyright © 2001 John Wiley & Sons, Ltd.
A modest but practical software process modeling technique for software process improvement
Authors: Ahonen Jarmo J. , Forsell Marko , Taskinen Sanna‐Kaisa 
Published: August 2002

AbstractOne of the main problems with software engineering is due to the difficulties in evaluating and improving our software processes, especially in the light of the fact that reuse depends on a process which supports it. Generally used approaches to the evaluation and improvement of software processes are based on the CMM, for example. In this paper we present a technique to improve software processes through modeling and evaluation. The presented technique is fairly easy to use, provides reasonably good results and requires only a fraction of resources required by CMM appraisals. Copyright © 2002 John Wiley & Sons, Ltd.