bluuebunny/crossref_metadata_2025_split huggingface dataset:
Marginalized models for longitudinal ordinal data with application to quality of life studies
Authors: Lee Keunbaik , Daniels Michael J. 
Published: July 2008

AbstractRandom effects are often used in generalized linear models to explain the serial dependence for longitudinal categorical data. Marginalized random effects models (MREMs) for the analysis of longitudinal binary data have been proposed to permit likelihood‐based estimation of marginal regression parameters. In this paper, we propose a model to extend the MREM to accommodate longitudinal ordinal data. Maximum marginal likelihood estimation is proposed utilizing quasi‐Newton algorithms with Monte Carlo integration of the random effects. Our approach is applied to analyze the quality of life data from a recent colorectal cancer clinical trial. Dropout occurs at a high rate and is often due to tumor progression or death. To deal with events due to progression/death, we used a mixture model for the joint distribution of longitudinal measures and progression/death times and use principal stratification to draw causal inferences about survivors. Copyright © 2008 John Wiley & Sons, Ltd.
Using tensor product splines in modeling exposure–time–response relationships: Application to the Colorado Plateau Uranium Miners cohort
Authors: Berhane Kiros , Hauptmann Michael , Langholz Bryan 
Published: July 2008

AbstractAn adequate depiction of exposure–time–response relationships is important in assessing public health implications of an occupational or environmental exposure. Recent advances have focused on flexible modeling of the overall shape of latency. Methods are needed to allow for varying shapes of latency under different exposure profiles. A tensor product spline model is proposed for describing exposure–response relationships for protracted time‐dependent occupational exposure histories in epidemiologic studies. The methods use flexible multi‐dimensional techniques to jointly model age, latency and exposure–response effects. In analyzing data from the Colorado Plateau Uranium Miners cohort, a model that allows for varying exposure‐dependent latency shapes is found to be superior to models that only allowed for an overall latency curve. Specifically, the model suggests that, at low exposure levels risk increased at short latencies followed by a slow decline for longer latency periods. On the other hand, risk was higher but did not change much by latency for higher exposure levels. The proposed methodology has the advantage of allowing for latency functions that vary by exposure levels and, conversely, exposure–response relationships that are influenced by the latency structure. Copyright © 2008 John Wiley & Sons, Ltd.
Estimation method of the semiparametric mixture cure gamma frailty model
Authors: Peng Yingwei , Zhang Jiajia 
Published: July 2008

AbstractMixture cure frailty model has been proposed to analyze censored survival data with a cured fraction and unobservable information among the uncured patients. Different from a usual mixture cure model, the frailty model is employed to model the latency component in the mixture cure frailty model. In this paper, we extend the mixture cure frailty model by incorporating covariates into both the cure rate and the latency distribution parts of the model and propose a semiparametric estimation method for the model. The Expectation Maximization (EM) algorithm and the multiple imputation method are employed to estimate parameters of interest. In the simulation study, we show that both estimation methods work well. To illustrate, we apply the model and the proposed methods to a data set of failure times from bone marrow transplant patients. Copyright © 2008 John Wiley & Sons, Ltd.
Comparison of the risk difference, risk ratio and odds ratio scales for quantifying the unadjusted intervention effect in cluster randomized trials
Authors: Ukoumunne Obioha C. , Forbes Andrew B. , Carlin John B. , Gulliford Martin C. 
Published: July 2008

AbstractThis paper evaluates methods for unadjusted analyses of binary outcomes in cluster randomized trials (CRTs). Under the generalized estimating equations (GEE) method the identity, log and logit link functions may be specified to make inferences on the risk difference, risk ratio and odds ratio scales, respectively. An alternative, ‘cluster‐level’, method applies the t‐test to summary statistics calculated for each cluster, using proportions, log proportions and log odds, to make inferences on the respective scales. Simulation was used to estimate the bias of the unadjusted intervention effect estimates and confidence interval coverage, generating data sets with different combinations of number of clusters, number of participants per cluster, intra‐cluster correlation coefficient ρ and intervention effect. When the identity link was specified, GEE had little bias and good coverage, performing slightly better than the log and logit link functions. The cluster‐level method provided unbiased point estimates when proportions were used to summarize the clusters. When the log proportion and log odds were used, however, the method often had markedly large bias for two reasons: (i) bias in the modified summary statistic used for cluster‐level estimation when a cluster has zero cases with the outcome of interest (arising when the number of participants sampled per cluster is small and the outcome prevalence is low) and (ii) asymptotically, the method estimates the ratio of geometric means of the cluster proportions or odds, respectively, between the trial arms rather than the ratio of arithmetic means. Copyright © 2008 John Wiley & Sons, Ltd.
Analysis of cross‐over designs with serial correlation within periods using semi‐parametric mixed models
Authors: Maringwa John T. , Geys Helena , Shkedy Ziv , Faes Christel , Molenberghs Geert , Aerts Marc , Van Ammel Karel , Teisman Ard , Bijnens Luc 
Published: July 2008

AbstractThe use of semi‐parametric mixed models has proven useful in a wide variety of settings. Here, we focus on the application of the methodology in the particular case of a cross‐over design with relatively long sequences of repeated measurements within each treatment period and for each subject. Other than an overall measure of the difference between each one of the experimental groups and the control group, specific time point comparisons may also be of interest. To that effect, we propose the use of flexible semi‐parametric mixed models, enabling the construction of simulation‐based simultaneous confidence bands. The bands take into account both between‐ and within‐subject variabilities, while simultaneously correcting for multiple time point comparisons. Owing to the relatively long sequences of measurements per subject, the presence of serially correlated errors is anticipated and investigated. We illustrate how several formulations of semi‐parametric mixed models can be fitted and the construction of simulation‐based simultaneous confidence bands using SAS PROC MIXED. Copyright © 2008 John Wiley & Sons, Ltd.
Incorporating validation subsets into discrete proportional hazards models for mismeasured outcomes
Authors: Magaret Amalia S. 
Published: July 2008

AbstractStandard proportional hazards methods are inappropriate for mismeasured outcomes. Previous work has shown that outcome mismeasurement can bias estimation of hazard ratios for covariates. We previously developed an adjusted proportional hazards method that can produce accurate hazard ratio estimates when outcome measurement is either non‐sensitive or non‐specific. That method requires that mismeasurement rates (the sensitivity and specificity of the diagnostic test) are known. Here, we develop an approach to handle unknown mismeasurement rates. We consider the case where the true failure status is known for a subset of subjects (the validation set) until the time of observed failure or censoring. Five methods of handling these mismeasured outcomes are described and compared. The first method uses only subjects on whom complete data are available (validation subset), whereas the second method uses only mismeasured outcomes (naive method). Three other methods include available data from both validated and non‐validated subjects. Through simulation, we show that inclusion of the non‐validated subjects can improve efficiency relative to use of the complete case data only and that inclusion of some true outcomes (the validation subset) can reduce bias relative to use of mismeasured outcomes only. We also compare the performance of the validation methods proposed using an example data set. Copyright © 2008 John Wiley & Sons, Ltd.
Bayesian bootstrap estimation of ROC curve
Authors: Gu Jiezhun , Ghosal Subhashis , Roy Anindya 
Published: July 2008

AbstractReceiver operating characteristic (ROC) curve is widely applied in measuring discriminatory ability of diagnostic or prognostic tests. This makes the ROC analysis one of the most active research areas in medical statistics. Many parametric and semiparametric estimation methods have been proposed for estimating the ROC curve and its functionals. In this paper, we propose the Bayesian bootstrap (BB), a fully nonparametric estimation method, for the ROC curve and its functionals, such as the area under the curve (AUC). The BB method offers a bandwidth‐free smoothing approach to the empirical estimate, and gives credible bounds. The accuracy of the estimate of the ROC curve in the simulation studies is examined by the integrated absolute error. In comparison with other existing curve estimation methods, the BB method performs well in terms of accuracy, robustness and simplicity. We also propose a procedure based on the BB approach to test the binormality assumption. Copyright © 2008 John Wiley & Sons, Ltd.
‘Smooth’ inference for survival functions with arbitrarily censored data
Authors: Doehler Kirsten , Davidian Marie 
Published: July 2008

AbstractWe propose a procedure for estimating the survival function of a time‐to‐event random variable under arbitrary patterns of censoring. The method is predicated on the mild assumption that the distribution of the random variable, and hence the survival function, has a density that lies in a class of ‘smooth’ densities whose elements can be represented by an infinite Hermite series. Truncation of the series yields a ‘parametric’ expression that can well approximate any plausible survival density, and hence survival function, provided the degree of truncation is suitably chosen. The representation admits a convenient expression for the likelihood for the ‘parameters’ in the approximation under arbitrary censoring/truncation that is straightforward to compute and maximize. A test statistic for comparing two survival functions, which is based on an integrated weighted difference of estimates of each under this representation, is proposed. Via simulation studies and application to a number of data sets, we demonstrate that the approach yields reliable inferences and can result in gains in efficiency over traditional nonparametric methods. Copyright © 2008 John Wiley & Sons, Ltd.
De‐stressing mommy: ameliorative association with dispositional optimism and resiliency
Authors: Baldwin Debora R. , Kennedy Donna L. , Armata Pamela 
Published: July 2008

AbstractThe purpose of this investigation was to examine the role of dispositional optimism on levels of stress, resiliency and salivary immunoglobulin A (IgA) in employed mothers. The participants, comprised of 37 mothers (26 married and 11 single), were asked to render a timed saliva sample and complete a questionnaire package (demographic sheet, stress, resiliency and optimism inventories). Results indicated that mothers who were more optimistic tended to report less distress and greater resiliency. Furthermore, life event stress was positively related to self‐reported levels of distress. Salivary IgA did not correlate significantly with the above psychological variables. These data provide additional support regarding the buffering effect of dispositional optimism on the stress experience and has practical implications for the cultivation of learned optimism in employed mothers. Copyright © 2008 John Wiley & Sons, Ltd.
Intrusive thoughts and everyday cognitive failures in Holocaust survivors
Authors: Boals Adriel 
Published: July 2008

AbstractPast research has found that the experiencing of a traumatic event can lead to detriments in lab‐based measures of cognitive abilities. However, there is only limited research on the impact of trauma on everyday cognitive functioning. In the current study, 13 Holocaust survivors completed measures of intrusive and avoidant thoughts concerning the Holocaust, the Cognitive Failures Questionnaire and a measure of lifetime physical health. The results revealed that intrusive thoughts predicted the frequency of everyday cognitive failures, whereas avoidance of Holocaust memories predicted lifetime physical health. These findings suggest that trauma not only affects lab‐based measures of cognitive abilities but also impacts everyday cognitive functioning. Copyright © 2008 John Wiley & Sons, Ltd.
Psychological impact and associated factors after disclosure of genetic test results concerning hereditary non‐polyposis colorectal cancer
Authors: Yamashita Manami , Okamura Hitoshi , Murakami Yoshie , Sugano Kokichi , Yoshida Teruhiko , Uchitomi Yosuke 
Published: July 2008

AbstractThe purpose of this study is to elucidate the psychological impact of disclosure of genetic test results concerning hereditary non‐polyposis colorectal cancer (HNPCC) and to assess factors associated with it, with particular focus on memory function. The subjects were persons who were suspected of having HNPCC and given the choice of undergoing genetic testing. The post‐genetic testing psychological impact was evaluated by means of the Impact of Event Scale‐Revised (IES‐R), and personality tendencies and memory function were evaluated. Final data were obtained from 46 subjects. The results of the genetic testing were ‘mutation‐positive’ in 18 subjects, ‘uninformative’ in 18 subjects, and ‘mutation‐negative’ in 10 subjects. Comparison of the IES‐R scores showed that they tended to be higher in the mutation‐positive group, but the differences were not statistically significant. The personality tendency ‘nervousness’ and verbal memory assessed prior to disclosure were significantly associated with total score on the IES‐R. Based on the results of this study it seems possible to minimize the risk of a psychological impact of disclosure of genetic test results by reassessing the follow‐up system for persons at high risk of a psychological impact. Copyright © 2008 John Wiley & Sons, Ltd.
Psychosocial indicators and distress in immigrants living in Italian reception centres
Authors: Toselli Stefania , Gualdi‐Russo Emanuela 
Published: July 2008

AbstractDespite the high rate of migration to Italy, there are still no comprehensive studies of psychosocial distress in the different groups of immigrants. The objective of the present study was to investigate the psychosocial status of immigrants living in Bologna (Italy). We conducted a cross‐sectional survey of 396 immigrants (313 males and 83 females) from Africa, Asia and eastern Europe (Senegalese, Moroccans, Tunisians, Pakistanis, Kosovars and Roma) using questionnaires administered by trained anthropologists. Except for Tunisians, the psychological distress and discomfort of the immigrant groups are low, and the perception of their quality of life and well‐being is good. In the groups that have spent more time in Italy, the percentage of subjects wishing to return to their native country is generally higher. Immigrants living in Bologna exhibit a good psychosocial state and seem to have positively interacted with their new environment. Copyright © 2008 John Wiley & Sons, Ltd.
Psychogenic heart disease—stress and the heart: a historical perspective
Authors: Stanley Robb O , Burrows Graham D 
Published: July 2008

AbstractAlthough ‘stress’ is accepted by the general population and patients with cardiac disease as a contributor to acute cardiac events and to the disease itself, this has not been universally accepted by the scientific community over the last century. Historically, research is not always helpful because it is unclear whether what is being researched is the cause of the cardiac event (e.g. myocardial infarction) or the underlying disease. A great deal of effort had been put into researching the concept of the coronary prone personality (i.e. Type A) with somewhat modest results. The shift in focus to the involvement of negative affect in cardiac disease has moved the field forward significantly. Recently, research has furthered our understanding of the mechanisms whereby stressful life experiences may interact with predispositions to experience the negative affects of anxiety, anger and depression (i.e. a feature of personality) and inherited cardiac disease proneness to result in both disease and acute events. Copyright © 2007 John Wiley & Sons, Ltd.
Mental stress is a cause of cardiovascular diseases: from scepticism to certainty
Authors: Esler Murray , Schwarz Rosemary , Alvarenga Marlies 
Published: July 2008

AbstractIntegrating into the clinical practice of medicine the recent evidence that psychiatric illness and mental stress contributes to the development of cardiovascular disease has not been a seamless process. The evidence for such a link, in fact, had been slow in materializing. The importance of acute mental stress as a trigger for cardiac catastrophes (acute myocardial infarction, sudden death) and of depressive illness as a cause of coronary heart disease, however, is now firmly established. But the spectre of workplace litigation still does hang over the field, clouding the arguments and polarizing medical opinion. Now that a consensus finally seems to have been reached that mental stress, including in the workplace, is an important cause of coronary heart disease and hypertension, it is hoped that the primary outcome will be the implementation of preventive measures to reduce stress in the workplace, such as worker empowerment to end the very adverse high demand/low job control scenario, rather than a rash of lawsuits. Copyright © 2008 John Wiley & Sons, Ltd.
State‐of‐the‐art: anxiety management in patients with implantable cardioverter defibrillators
Authors: Sears Samuel F. , Vazquez Lauren D. , Matchett Melissa , Pitzalis Mariavittoria 
Published: July 2008

AbstractThrough large‐scale clinical trials, the implantable cardioverter defibrillator (ICD) has been established as the treatment of choice for primary and secondary prevention of sudden cardiac death. Although the ICD offers a confirmed mortality benefit, it may incite psychological adjustment issues within recipients. The most predominant form of psychological morbidity for ICD patients is anxiety. The prevalence of anxiety is well documented within the context of cardiac patients; however, ICD recipients often present with device‐specific concerns, including shock and death anxiety. Therefore, the interventions for these patients must be tailored to their unique concerns. This article will discuss forms and manifestations of anxiety within the ICD patient population, followed by an exploration of the components of psychosocial interventions found to be effective with these patients. Copyright © 2008 John Wiley & Sons, Ltd.
Impacts of disasters: comparisons of several worries in Turkey
Authors: Kasapoğlu Aytül , Turan Feryal , Dönmez Ali 
Published: July 2008

AbstractThe aim of this paper is to define respondents' levels of worries and to find out the main predictors of each worry factor by comparing the results of earthquake (2001) and bird flu (2006) studies carried out in Turkey. Assuming that the critical power‐conflict perspective was appropriate; several types of worries, namely, traffic accidents, natural disasters, unemployment, health and sickness, nuclear plants, war and terrorism, and environmental problems defined by Kamano have been analysed using parametric and non‐parametric statistical significance tests. The results revealed that earthquake hazards affected respondents' level of worries more than bird flu disease mainly because of the enormous economic and human losses of the 1999 earthquake. It was also found that the main predictors were not the same for both studies: the education variable was more effective on the level of worries of earthquake survivors, and gender was more influential for the bird flu study. Copyright © 2008 John Wiley & Sons, Ltd.
Mining temporal rules for software maintenance
Authors: Lo David , Khoo Siau‐Cheng , Liu Chao 
Published: July 2008

AbstractSoftware evolution incurs difficulties in program comprehension and software verification, and hence it increases the cost of software maintenance. In this study, we propose a novel technique to mine from program execution traces a sound and complete set of statistically significant temporal rules of arbitrary lengths. The extracted temporal rules reveal invariants that the program observes, and will consequently guide developers to understand the program behaviors, and facilitate all downstream applications such as verification and debugging. Different from previous studies that were restricted to mining two‐event rules (e.g., 〈lock〉→〈unlock〉), our algorithm discovers rules of arbitrary lengths. In order to facilitate downstream applications, we represent the mined rules as temporal logic expressions, so that existing model checkers or other formal analysis toolkit can readily consume our mining results. Performance studies on benchmark data sets and a case study on an industrial system have been performed to show the scalability and utility of our approach. We performed case studies on JBoss application server and a buggy concurrent versions system application, and the result clearly demonstrates the usefulness of our technique in recovering underlying program designs and detecting bugs. Copyright © 2008 John Wiley & Sons, Ltd.
Random variate generator
Authors: Laracy Joseph R. 
Published: July 2008

AbstractAs the use of computer simulation grows in a variety of science and engineering fields, the quality of random variate generators becomes increasingly important. Unfortunately, a number of standard implementations are grossly inadequate and exhibit poor statistical properties. This paper presents a software pattern for efficiently implementing an extensible, high‐quality random variate generator. Copyright © 2008 John Wiley & Sons, Ltd.
Automotive–adept: A lightweight assessment method for the automotive software industry
Authors: Mc Caffery Fergal , Richardson Ita , Moller Peter a 
Published: July 2008

AbstractIn this article we describe how a lightweight assessment method was developed to educate Irish software small‐ to medium‐sized enterprises (SMEs)1in relation to becoming automotive software suppliers. The main goal of this assessment method is to provide software SMEs with a software process improvement (SPI) path to becoming automotive software suppliers. Copyright © 2008 John Wiley & Sons, Ltd.