bluuebunny/crossref_metadata_2025 huggingface dataset:
The Cost-Effectiveness of Magnetic Resonance Imaging for Patients with Equivocal Neurological Symptoms
Authors: Mushlin Alvin I. , Mooney Cathleen , Holloway Robert G. , Detsky Allan S. , Mattson David H. , Phelps Charles E.
Published: March 2009

Objective: To determine the incremental cost-effectiveness of magnetic resonance imaging (MRI) and computed tomography (CT) in young adults presenting with equivocal neurological signs and symptoms. Designs and methods: A decision analysis of long-term survival using accuracy data from a diagnostic technology assessment of MRI and CT in patients with suspected multiple sclerosis, information from the medical literature, and clinical assumptions. Main results: In the baseline analysis, at 30% likelihood of an underlying neurologic disease, MRI use has an incremental cost of $101,670 for each additional quality-adjusted life-year saved compared with $20,290 for CT use. As the probability of disease increases, further MRI use becomes a cost-effective alternative costing $30,000 for each quality-adjusted life-year saved. If a negative MRI result provides reassurance, the incremental costs of immediate MRI use decreases and falls below $25,000 for each quality-adjusted life-year saved no matter the likelihood of disease. Conclusions: For most individuals with neurological symptoms or signs, CT imaging is cost-effective while MR imaging is not. The cost-effectiveness of MRI use, however, improves as the likelihood of an underlying neurological disease increases. For selected patients who highly value diagnostic information, MRI is a reasonable and cost-effective use of medical resources when even the likelihood of disease is quite low (5%).
Priority Setting for Health Technology Assessment: Theoretical Considerations and Practical Approaches: A paper produced by the Priority Setting Subgroup of the EUR-ASSESS Project
Authors: Henshall Chris , Oortwijn Wija , Stevens Andrew , Granados Alicia , Banta David
Published: March 2009

This report is about setting priorities for health technology assessment (HTA). HTA examines systematically the consequences of the application of health technologies (broadly defined to include any health care intervention) to support decision making in policy and practice. Only a fraction of existing health technologies have been formally evaluated, and many more appear each year. Resources for HTA are, however, limited so that priorities have to be set, whether explicitly or implicitly. The aim of setting priorities for HTA should be to identify those assessments that offer the greatest benefits in relation to their cost, and thus to maximize the benefit derived from investments in HTA.
Selecting the Best Renal Function Tests:A Meta-analysis of Diagnostic Studies
Authors: Campens Dirk , Buntinx Frank
Published: March 2009

A literature review compared the results of different kidney function tests using the inulin clearance or similar methods as a gold standard. The methodological strength of the available studies was weak. For the time being, the calculated creatinine clearance using formula, is a first choice, especially in general practice.
Evaluating the Impact of Health Care Information Systems
Authors: Anderson James G. , Aydin Carolyn E.
Published: March 2009

Evaluating the impact of computer-based medical information systems requires not only an understanding of computer technology but also an understanding of complex social and behavioral processes. This essay discusses the need for evaluation of health care information systems, a set of evaluation questions based on assumptions about the impact of technology on organizations, and recommendations for reducing barriers to the implementation of health care information systems.
The National Patient Library: Evidence-based Information for Consumers
Authors: Lerner Jeffrey C.
Published: March 2009

A National Patient Library, a public/private partnership, is proposed to identify and vet information for consumers. Library staff will help tailor general information to consumers' specific needs. The library includes an electronic network. The principal focus of the library's information is controversial and experimental procedures, Pharmaceuticals, and medical devices.
A Model for Estimating the Cost-Utility of Clinical Audit: The Example of Thrombolysis for Suspected Acute Myocardial Infarction
Authors: Robinson Michael B. , Thompson Elizabeth , Black Nick A.
Published: March 2009

Economic evaluation of quality assurance programs is often called for but rarely reported. A study was designed to estimate the cost-utility of audit of thrombolysis in four U.K. district general hospitals, using the quality-adjusted life year. Although the results obtained were imprecise, the model used could be applied in future evaluations.
Commentary
Authors: Neuhauser Duncan
Published: March 2009

When I was a doctoral student in health care administration at the University of Chicago, I worked with Odin Anderson, who introduced me to Osier Peterson and Bjprn Smedby. Odin first took me to Sweden in 1966. In early 1970, I met Lee Lusted and heard about clinical decision analysis. My interests, then as now, were the costs and outcomes of hospital care, although the methods I have used to address these problems have varied over time.
Costing Methods in the Canadian Literature on the Economic Evaluation of Health Care: A Survey and Assessment
Authors: Jacobs Philip , Bachynsky John
Published: March 2009

We reviewed the Canadian literature on cost-effectiveness from 1980–1995 with regard to costing methodologies. We abstracted each study using a list of data elements that describe costing methodology, and evaluated costing methodologies in the light of biases in costing methods, site, and case-mix selection.
The Diffusion and Use of Diagnostic Imaging Equipment in France
Authors: Fagnani F. , Moatti J. P. , Weill C.
Published: March 2009

The paper presents a French national survey on diagnostic imaging equipment and activity showing that conventional x-ray radiology still dominates and that the rate of diffusion of technological innovations has been very different, being slower than in other industrialized countries for such technologies as CT scanners, nuclear medicine, and magnetic resonance imaging, but on the other hand, very quick for ultrasound and digital angiography.

The variety of regulations for this equipment, although it plays an important role, is not sufficient to explain these differences in the rate of diffusion. The paper shows that other explanatory variables must be taken into account, at least in the French context: the situation of the domestic biomedicai industry, the relations between private and public sectors of health care delivery, and even the “technical” culture and tradition of French radiologists.
What Determines the Choice of Procedure in Stress Incontinence Surgery?: The Use of Multilevel Modeling
Authors: Griffiths Joanne M. , Black Nicholas A. , Pope Catherine , Stanley Jenny , Bowling Ann , Abel Paul D.
Published: March 2009

The purpose of this study was to identify the determinants of choice of surgical procedure (anterior colporrhaphy, colposuspension, or needle suspension) to treat stress incontinence in women. We used multilevel modeling of data on 271 patients in 18 hospitals in England in 1993–94. Patient-related factors included sociodemographic details, anatomical diagnosis, symptom severity, symptom impact, previous treatment, parity, comorbidity, and general health status. Surgeon-related factors were specialty, grade, and annual volume of procedures undertaken. Hospital teaching status was considered. Some patient-related factors were associated with choice of procedure: women with a concomitant genital prolapse, with a history of high parity, and with no previous nonsurgical treatment were more likely to undergo an anterior colporrhaphy than a colposuspension or needle suspension (although this finding could be confounded by surgical specialty). In addition, women were more likely to be treated by colposuspension if their surgeon specialized in incontinence surgery (measured by annual volume of cases). Finally, being treated by needle suspension depended on there being a consultant surgeon familiar with the procedure at the hospital attended. While choice of surgical procedure depends partly on the patient's anatomical diagnosis, it is also dependent on the specialty of the surgeon whom she consults and the hospital that she attends. This variability, in turn, could have implications for the patient (as the relative effectiveness of the different procedures is unknown) and for the purchasers of care (as the relative cost-effectiveness of procedures is also unknown).
An Economic Evaluation of Energy-Absorbing Flooring to Prevent Hip Fractures
Authors: Zacker Christopher , Shea Dennis
Published: March 2009

An economic evaluation of energy-absorbing flooring designed to prevent hip fractures revealed a payback period of 10½ years if only direct costs avoided were evaluated and just over 11 months when direct and indirect costs were included. Cost-effectiveness ratios of less than $0 per hip fracture prevented and life year saved were also estimated.
An Assessment of Picture Archiving and Communication Systems (PACS): The Case Study of the SMZO Project
Authors: Wild Claudia , Peissl Walter , Tellioglu Hilda
Published: March 2009

In order to make rational decisions for further implementation of picture archiving and communication systems (PACS) in Viennese community hospitals, an assessment of the Sozialmedizinisches Zentrum Ost (SMZO) project was launched by the Viennese community hospital financing body. The aim of the technology assessment was to look at the experiences of day-to-day practice, organizational aspects of, and obstacles to developing the full potential of the PACS installation. The study analyzes the conditions for employment of digital radiology, gathers the experiences of national and international projects, and presents a view on critical points, from which options for further implementation can be derived. In the center of interest stood work organization, handling and user attitudes, perceptions of radiologists and clinicians, realism of expectations regarding economic efficiency, technical aspects, and influence of quality of medical care.
Teaching Quantitative Approaches to the Use of Diagnostic Tests and Procedures
Authors: Panzer Robert J. , Griner Paul F.
Published: March 2009

Pressures to contain health care costs have challenged physicians to be more discriminating in the use of medical technology. Particularly important is the need to apply diagnostic technology selectively since the costs of diagnostic tests and procedures may account for as much as one quarter of total hospital costs and a smaller but substantial proportion of ambulatory care costs.
The Public: Education and Pressures Relative to Technologic Developments
Authors: Black Douglas
Published: March 2009

The title which I have been given suggests that in my particular consideration of technology the emphasis should be not on professional attitudes, but on public attitudes, and what might be done to inform and if necessary improve them. At first glance, a sensible approach might be to conduct some kind of survey among “the public” to discover what proportion of people hold particular attitudes towards technology. With little in the way of regret, I shall foreswear that approach, not because I am unacquainted with such surveys, but because I perhaps know them too well. If you ask a completely unloaded question, such as “What is your view of medical technology?”, you will probably get answers, but you will not be able to determine how much they are preconditioned by how much the person knows, and in particular how any recent experience of medical investigation has turned out. That in turn may owe more to the nature of his problem than to the skill with which investigations have been selected and performed. On the other hand, if you ask loaded questions, such as “Is medical technology free of risks?,” you will bias the proportion of replies, and still find the answer no easier to interpret.
An Early System for the Identification and Assessment of Future Health Care Technology: The Dutch STG Project
Authors: David Banta H. , Gelijns Annetine
Published: March 2009

This article is based on the report, Anticipating and Assessing Health Care Technology, written in the Netherlands between 1985–1988. The project was carried out because of increasing concern in the Dutch Ministry of Health (STG, then WVC) about the costs and benefits of new technologies for health care. At that time, there were no established models for early identification, so the project was not only the most extensive such effort to that date, but had to develop its own methods. Overseen by a special commission, the project staff identified many future and emerging technologies in health care and assessed selected technologies. Although the actual information produced was quickly dated and the project was discontinued in 1988, it did stimulate the Ministry of Health to ask the Dutch Health Council (Gezondheidsraad) to continuously identify important new technologies. The reports also demonstrated the potential usefulness of such an effort to Dutch policy makers, and probably to those in other countries as well.
Implementing Early Warning Messages on Emerging Health Technologies
Authors: Mowatt Graham , Thomson Mary Ann , Grimshaw Jeremy , Grant Adrian
Published: March 2009

The purpose of this study was to determine how horizon-scanning organizations can encourage the implementation of recommendations contained in their early warning messages about emerging health technologies. We reviewed the conclusions of the EUR-ASSESS Project Subgroup report on dissemination and impact, an overview of systematic reviews of interventions to promote implementation of research findings by health care professionals, and various Cochrane Effective Practice and Organisation of Care Group protocols and reviews. The evidence on the effectiveness of different implementation strategies aimed at distinct target groups is of variable quality. There is some evidence from rigorous study designs on the effectiveness of strategies designed to influence the behavior of health care professionals; the quality of the evidence relating to policy makers and the general public is more limited. Horizon-scanning organizations can improve the likelihood of their recommendations being acted upon by developing active implementation strategies based on the best available evidence, establishing links with key groups, and directing early warning messages at specific target audiences. Given the relative lack of good quality evidence, it is important that implementation strategies be rigorously evaluated to determine their effectiveness.
The Identification of New Health Care Technologies by the Health Council of the Netherlands
Authors: ten Velden Gabriël H. M.
Published: March 2009

The article gives a global overview of the 14 years of signposting experience of the Health Council of the Netherlands. The Council signals new health care technologies and emerging health care problems in briefs, comprehensive reports, and bulletins. Its main purpose is to provide the government with timely information to support rational policy decision making.
Early Warning of New Health Care Technologies in the United Kingdom
Authors: Stevens Andrew , Packer Claire , Robert Glenn
Published: March 2009

In this paper we describe the present range of organizations that have a role in the early warning of new and emerging health care technologies in the United Kingdom. We discuss in more detail the processes and prioritization criteria used by the U.K. horizon-scanning project for the NHS Health Technology Assessment Programme, and the principal methods of technology identification for the horizon-scanning project are outlined. The United Kingdom plans to develop an integrated system for the identification of technologies for commercial planning, health service research prioritization, financial planning, and provision of information to policy makers, purchasers, and providers of health care.
How well do Investigators Estimate Results in Advance?: A Methodological Study from a Multinational Epidemiological Survey on Hip Fracture Risks
Authors: Allander Erik
Published: March 2009

The aim of the present study was to compare the factual results with the perception of results by the expert investigators involved in a major epidemiological study on risk factors for hip fracture, the Mediterranean Osteoporosis Study (MEDOS), and to do so before the actual results were known. A selection of 30 questions were used from the original MEDOS questionnaire to obtain estimates of selected key risk factors from the 14 participating experts. Ten investigators participated, six of whom filled out the questionnaire completely; these six questionnaires were used for the analysis. The population was estimated to be younger, to have better functional capacity, and to be more subjected to preventive activities than the actual survey data showed. Several methodological problems are explored.
Outcome of Total Hip Replacement in Japan and England:Comparison of Two Retrospective Cohorts
Authors: Imamura Kyoko , Black Nick
Published: March 2009

Two retrospective cohorts of patients who had undergone a primary total hip replacement (THR) were studied in Japan and England. We analyzed information from hospital case notes and self-administered questionnaires. THR was highly effective in both countries, with significant improvements in morbidity and health status. There were, however, important differences in clinical management and outcome. Japanese patients were more likely to be treated under regional anesthesia by means of an anterior/anterolateral incision, to be transfused, to have a prosthesis implanted without cement, and to stay longer in the hospital. A higher rate of serious in-hospital complications occurred in England, mostly due to the high frequency of hypotension. The incidences of minor complications were consistent with known differences in risks between the two countries. The persistent postoperative perception of limping reported by the English patients was unexpected.
The Effectiveness of Bone Density Measurement and Associated Treatments for Prevention of Fractures:An International Collaborative Review
Authors: Hailey David , Sampietro-colom Laura , Marshall Deborah , Rico Rosa , Granados Alicia , Asua José
Published: March 2009

This review assesses the evidence regarding the effectiveness of bone density measurement (BDM) screening and related interventions—hormone replacement therapy (HRT) and intranasal salmon calcitonin (SCT[N])—in menopausal women to prevent fractures in later life. Data sources included systematic reviews of evidence and relevant primary studies identified through literature searches on MEDLINE and EMBASE. Study selection included trials of BDM screening programs, prospective studies exam-ining the predictive value of BDM, randomized controlled trials, cohort studies, and case-controlstudies of HRT and SCT(N). The evidence was evaluated using a classification system incorporatingstudy design and quality. Outcomes were measured in terms of relative risk of fracture for a 1 SDdecrease in bone mineral density below the age-adjusted mean, relative risks or odds ratios forfractures associated with treatments, and proportion of hip fractures potentially prevented by BDMscreening linked to treatments. Fair evidence from prospective cohort studies suggests that BDMcan predict the risk of fractures, but not with high accuracy. Fair evidence from low-quality randomizedcontrolled trials and observational studies suggests that HRT and SCT(N) are efficacious in preventingfractures. Good evidence supports the efficacy of these treatments in preserving bone mass, butthere is fair evidence that the effect wears off after cessation of therapy. There is little evidence onthe impact of screening menopausal women with BDM in association with HRT or SCT(N) treatment.Estimates based on combining existing evidence regarding the predictive value of BDM and efficacyof HRT suggests that 1–7% of hip fractures might be prevented.
Anticipating the Consequences for the Primary Therapy of Breast Cancer after Introducing Screening: A More Global Picture for Health Care Policy Making
Authors: Borràs Josep M. , Espinas Josep A. , Beemsterboer Petra M. M. , Granados Alicia , Koning Harry J. De
Published: March 2009

A breast cancer screening program mainly aims at reducing mortality. However, it also has an effect, often not assessed, on the utilization of health care resources that is relevant to health care policy making. Using a simulation model, this paper forecasts the impact of introducing a breast cancer screening program on the utilization of resources for the primary therapy of breast cancer. The most important consequences from a health care point of view will be an increased use of breast-conserving therapy and an increased need for postoperative radiotherapy; there will also be a higher number of women diagnosed with noninvasive breast cancer. The results of this study could provide support for health care decision making by showing the consequences of policy decisions on the introduction of screening programs for health care utilization.
Introducing Information Technology in the Clinical Setting: Lessons Learned in a Trauma Center
Authors: Paré Guy , Elam Joyce J.
Published: March 2009

Using a case study methodology, we examined the implementation of a nursing flow sheet system in the trauma center of a large, not-for-profit, teaching hospital. Findings add new insights to the existing body of knowledge in the information technology and medical informatics fields. First, results reveal that the success of clinical information systems requires a proactive stance where key actors anticipate and address the challenges ahead and capitalize on opportunities. Second, empirical evidence indicates that project outcomes ultimately depend on how the implementation process is managed and what the organization and its members do with the system once it is introduced. Finally, the case at hand shows that the nature and overall quality of the implementation strategy can be largely predicted by the key actors involved in the project, given their own background, skills, interest, and level of motivation.
Evidence Into Practice:Prescribing Selective Serotonin Reuptake Inhibitors
Authors: Freemantle Nick , Mason James M. , Watt Ian
Published: March 2009

This descriptive analysis examines prescribing trends of antidepressants in English primary care, providing analysis of NHS reimbursement data for groups of antidepressants between 1989 and 1994. Prescribing trends seem unaffected by the release of information on the effectiveness and costeffectiveness of antidepressant drugs. We found that simple distribution of the results of health technology assessments may not be sufficient to influence practice.
Epidemiology of Prematurity
Authors: Sinclair John C.
Published: March 2009

The two components of low birth weight — preterm delivery and fetal growth retardation — lead singly or in combination to a heavy burden of mortality, short- and long-term morbidity, and high medical and social costs. Although different types of long-term morbidity are still being identified, the primary focus of concern has been neurodevelopmental disability resulting from the cerebral palsies, hydrocephalus, and visual and auditory deficits among survivors of very low birth weight. Additional special risks in such infants include chronic lung disease, acute lower respiratory infections, and rehospitalization in infancy and early childhood.
Epidemiology of Neonatal Disorders of Respiration
Authors: Hjalmarson Ola
Published: March 2009

It is well known that signs of respiratory distress or disease (RD), such as high breathing frequency, chest wall retractions, grunting, and cyanosis, are common in newborn infants. The signs may be very transient or develop into a potentially life-threatening condition. When they are first observed, they often have a very ambiguous prognostic significance.
High-Frequency Oscillatory Ventilation
Authors: Hodson W. Alan
Published: March 2009

The improved survival rate of premature infants with respiratory failure is attributable to advances in mechanical ventilation, although an adverse consequence has been an increased incidence of bronchopulmonary dysplasia (BPD) (1;32). Positive pressure ventilation with its attendant “barotrauma” is suspected in the causation of BPD. While many attempts to alter respirator variables, such as pressure and time components, have produced optimal patterns for gas exchange, evidence is lacking to support any one pattern that minimizes the incidence of chronic lung injury. The high incidence of BPD has promoted a search for alternative methods of ventilation that might reduce lung injury through a reduction in peak pressure applied to the lung. Additional motivation has come from the need for oxygenation when mechanical ventilation has failed or pulmonary interstitial emphysema has developed. Less compelling reasons have come from the desire to avoid high swings in thoracic pressure that might adversely affect cardiac output, venous return, and cerebral blood flow.
Pathophysiology of Neonatal Lung Injury
Authors: Bland Richard D.
Published: March 2009

Respiratory distress in newborn and young infants often develops as a result of acute lung injury, in which disruption of the normal barrier function of the pulmonary endothelium and epithelium causes protein-rich interstitial and alveolar edema. Several conditions may initiate acute lung injury, including aspiration of meconium or gastric contents, bacterial or viral infection, overzealous resuscitation, and birth associated with incomplete lung development that requires ventilatory support with positivepressure mechanical ventilation and high concentrations of inspired oxygen. The latter condition usually occurs after premature birth, but it also may occur as a consequence of impaired fetal lung growth secondary to diaphragmatic hernia or chest compression from lack of liquid in the amniotic cavity. Acute lung injury sometimes progresses to a chronic form of lung disease, which is characterized by edema, fibrosis, airway distortion, and nonuniform inflation of the lungs.
Control of Blood Pressure and the Distribution of Blood Flow
Authors: Versmold Hans T.
Published: March 2009

Systemic blood pressure (BP) is the product of cardiac output and total peripheral resistance. Cardiac output is controlled by the heart rate, myocardial contractility, preload, and afterload. Vascular resistance (vascular hindrance × viscosity) is under local autoregulation and general neurohumoral control through sympathetic adrenergic innervation and circulating catecholamines. Sympathetic innovation predominates in organs receivingflowin excess of their metabolic demands (skin, splanchnic organs, kidney), while innervation is poor and autoregulation predominates in the brain and heart. The distribution of blood flow depends on the relative resistances of the organ circulations. During stress (hypoxia, low cardiac output), a raise in adrenergic tone and in circulating catecholamines leads to preferential vasoconstriction in highly innervated organs, so that blood flow is directed to the brain and heart. Catecholamines also control the levels of the vasoconstrictors renin, angiotensin II, and vasopressin. These general principles also apply to the neonate.
Hemorrhagic and Ischemic Lesions of the Perinatal Brain
Authors: De Vries Linda , Dubowitz Lilly M. S.
Published: March 2009

The introduction of noninvasive imaging techniques allowed diagnosis of intracranial pathology in the newborn infant during life, which previously was only possible at postmortem. This has stimulated new interest in correlating pathology with the pathophysiological changes that lead to these events, the neurological signs associated with them, and their ultimate effect on the neurological state of the survivors.
Prevention and Treatment of Postasphyxial Cerebral Damage
Authors: Raivio Kari O.
Published: March 2009

Prevention and treatment of postasphyxial, i.e. hypoxic-ischemic, brain damage can be considered at various levels or stages of the process. The first approach is based on epidemiological studies, which typically allow the delineation ofrisk factorsfor cerebral damage. By trying to eliminate or reduce such factors, one may influence the incidence of the disorder. At the second stage, the actualpathogenetic mechanisms, e.g. hypoxia or hypotension, leading to brain damage may be preventable or treatable. Finally,limiting the extentof the lesion immediately after the event may be possible.
What is the Actual Cost of Neonatal Intensive Care?
Authors: Ewald Uwe
Published: March 2009

Health care providers are increasingly concerned about the rising costs of the total health care system, which is now approaching 10–12% of the gross national product (GNP). The long-term decrease in birth rates and the prolonged mean length of life of the population shifts the age pyramid to older ages, bringing a higher demand for health care at increasing costs. Another explanation for the rising health care expenditure is the application of modern medical technologies in the treatment of the terminally or critically ill at any age. It has been estimated that 1 of every 7 health care dollars is now consumed by patients who are within 6 months of the end of their lives (5).
Norwegian Experiences: Competence of the Providers and Compliance to the Treatment Program for Antenatal Care in Norway
Authors: Backe Bjørn
Published: March 2009

Antenatal care was established in Norway during the 1930s. Unlike the other Nordic countries, care is provided by general practitioners, not be midwives. Guidelines were first issued in 1984 after a debate about the quality of the care. This article reports providers' compliance to important parts of the guidelines.
Screening for Hypertension in Pregnancy
Authors: Goldenberg Robert L.
Published: March 2009

The literature dealing with screening for hypertension in pregnancy was reviewed. No level of blood pressure or any other factor provides a guarantee of no risk for the development of preeclampsia. However, higher blood pressure in early pregnancy and a failure to decrease blood pressure in midpregnancy are both associated with the development of preeclampsia. The development of proteinuria, rather than the level of blood pressure, is the best predictor of poor pregnancy outcome. Multiparas, especially those with severe chronic hypertension who develop preeclampsia, are at greatest risk of poor pregnancy outcome.
Diagnostic Methods for Pregnancy Hypertension: Significance of Standardized Conditions
Authors: Åberg Anders
Published: March 2009

Standardized conditions for blood pressure measurements and strict definitions of systolic and diastolic blood pressure are essential for a consequent management of hypertension during pregnancy. In Sweden, it has been agreed to measure blood pressure with the pregnant women sitting in upright position. Home-monitoring of blood pressure is recommended in women at risk of preeclampsia.
Cost-Effectiveness of Present Programs for Detection of Asymptomatic Hypertension in Relation to the Severity of Hypertension Andproteinuric Hypertension
Authors: Hall Marion , Campbell Doris
Published: March 2009

Proteinuric hypertension is an important cause of maternal and perinatal mortality. Eclampsia cannot always be prevented. The likelihood of identifying a new case of proteinuric hypertension at any particular visit is very low using traditional antenatal care schedules, and care could be focused on women at higher risk.
Predictive Consequences of Using Conditioning or Causal Variables
Authors: Granger C.W.J. , Thomson P. J.
Published: March 2009

Forecasts based on two information sets, one of which includes the other plus additional causal variables are considered. Given a general cost function of forecast errors, it is shown that the expected cost is smaller for the information set that includes the causal variables.
Estimation of the Covariance Matrix of the Least-Squares Regression Coefficients When the Disturbance Covariance Matrix Is of Unknown Form
Authors: Keener Robert W. , Kmenta Jan , Weber Neville C.
Published: March 2009

This paper deals with the problem of estimating the covariance matrix of the least-squares regression coefficients under heteroskedasticity and/or autocorrelation of unknown form. We consider an estimator proposed by White [17] and give a relatively simple proof of its consistency. Our proof is based on more easily verifiable conditions than those of White. An alternative estimator with improved small sample properties is also presented.
Robust M-Tests
Authors: Peracchi Franco
Published: March 2009

This paper investigates the local robustness properties of a general class of multidimensional tests based on M-estimators. These tests are shown to inherit the efficiency and robustness properties of the estimators on which they are based. In particular, it is shown that small perturbations of the distribution of the observations can have arbitrarily large effects on the asymptotic level and power of tests based on estimators that do not possess a bounded influence function. An asymptotic ‘admissibility’ result is also presented, which provides a justification for tests based on optimal bounded-influence estimators.
The Et Interview: Professor Sir Richard Stone
Authors: Pesaran M. Hashem
Published: March 2009

Sir Richard Stone, knighted in 1978 and Nobel Laureate in Economics in 1984, is one of the pioneering architects of national income and social accounts, and is one of the few economists of his generation to have faced the challenge of economics as a science by combining theory and measurement within a cohesive framework. He was awarded the Nobel Prize in Economics for his “fundamental contributions to the development of national accounts,” but he has made equally significant contributions to the empirical analysis of consumer behavior. His work on the “Growth Project” has also been instrumental in the development of appropriate econometric methodology for the construction and the analysis of large disaggregated macroeconometric models.

Throughout his long and productive career, stretching over more than half a century, Stone has been an inspiration to applied econometricians all over the world. His influence goes well beyond his written work. He has made a lasting impact on the large number of (now prominent) economists and statisticians who visited the Department of Applied Economics when he was its Director. He is a scientist, a scholar, and above all, a gentleman. He gives generously of himself and is always willing to help the cause of applied econometrics. He has been a Fellow of King's College, Cambridge since 1945 and has served as the President of the Econometric Society (in 1955) and the President of the Royal Economic Society (during 1978–1980). In the interview that follows, Richard Stone gives us a delightful account of his time as a student at Westminster School, his early introduction to economics at Cambridge University, and he shares with us his memories and thoughts on a long and productive career. The interview was conducted in Stones' magnificent private library in Cambridge, and I hope that readers enjoy reading the interview as much as I enjoyed recording it.

Further details of Richard Stone's biography and research activities can be found in:

Deaton, A. Stone, John Richard Nicholas. In J. Eatwell, M. Milgate and P. Newman (eds.), The New Palgrave: A Dictionary of Economics, Vol. 4, pp. 509–512. London: Macmillan, 1987.

Stone, J.R.N. An autobiographical sketch. In Les Prix Nobel 1984. Stockholm: Almquist and Wicksell International, 1985.
The Bias of Forecasts from a First-Order Autoregression
Authors: Magnus Jan R. , Pesaran Bahram
Published: March 2009

The exact finite sample behavior is investigated on the bias of multiperiod leastsquares forecasts in the normal autoregressive model yt = α + βyt–1 + ut. Necessary and sufficient conditions are given for the existence of the bias and an expression is presented which we use to obtain exact numerical results for finite samples. The unit root and near unit root behavior is studied in detail and some popular preconceptions about the behavior of the bias are shown to be false.
Test Consistency with Varying Sampling Frequency
Authors: Perron Pierre
Published: March 2009

This paper considers the consistency property of some test statistics based on a time series of data. While the usual consistency criterion is based on keeping the sampling interval fixed, we let the sampling interval take any equispaced path as the sample size increases to infinity. We consider tests of the null hypotheses of the random walk and randomness against positive autocorrelation (stationary or explosive). We show that tests of the unit root hypothesis based on the first-order correlation coefficient of the original data are consistent as long as the span of the data is increasing. Tests of the same hypothesis based on the first-order correlation coefficient of the first-differenced data are consistent against stationary alternatives only if the span is increasing at a rate greater than T½, where T is the sample size. On the other hand, tests of the randomness hypothesis based on the first-order correlation coefficient applied to the original data are consistent as long as the span is not increasing too fast. We provide Monte Carlo evidence on the power, in finite samples, of the tests Studied allowing various combinations of span and sampling frequencies. It is found that the consistency properties summarize well the behavior of the power in finite samples. The power of tests for a unit root is more influenced by the span than the number of observations while tests of randomness are more powerful when a small sampling frequency is available.
Noninvertibility and Pseudo-Maximum Likelihood Estimation of Misspecified ARMA Models
Authors: Pötscher B.M.
Published: March 2009

Recently Tanaka and Satchell [11] investigated the limiting properties of local maximizers of the Gaussian pseudo-likelihood function of a misspecified moving average model of order one in case the spectral density of the data process has a zero at frequency zero. We show that pseudo-maximum likelihood estimators in the narrower sense, that is, global maximizers of the Gaussian pseudo-likelihood function, may exhibit behavior drastically different from that of the local maximizers. Some general results on the limiting behavior of pseudo-maximum likelihood estimators in potentially misspecified ARMA models are also presented.
The Joint Distribution of Forecast Errors in the AR(1) Model
Authors: Kemp Gordon C.R.
Published: March 2009

Second-order asymptotic expansion approximations to the joint distributions of dynamic forecast errors and of static forecast errors in the stationary Gaussian pure AR(1) model are derived. The approximation to the dynamic forecast errors distribution can be expressed as a multivariate normal distribution with modified mean vector and covariance matrix, thus generalizing the results of Phillips [12]. However, the approximation to the static forecast errors distribution includes skewness and kurtosis terms. Thus the class of multivariate normal distributions does not provide as good approximations (in terms of error convergence rates) to the distributions of the static forecast errors as to the distributions of the dynamic forecast errors. These results cast some doubt on the appropriateness of model validation procedures, such as Chow tests, which use the static forecast errors and implicitly assume that these have a distribution which is well approximated by a multivariate normal.
Discrete Models for Estimating General Linear Continuous Time Systems
Authors: Chambers Marcus J.
Published: March 2009

This paper derives discrete models for estimating systems of both first- and second-order linear differential equations in which derivatives of the exogenous variables appear in addition to their levels.
Interpretation of Graphs that Compare the Distribution Functions of Estimators
Authors: Moulton Brent R.
Published: March 2009

In this paper I examine graphical comparisons of one-dimensional (or marginal) distribution functions of alternative estimators. It is shown that areas under the c.d.f. (cumulative distribution function) curve can be given a decision-theoretic interpretation as risk under a bounded absolute-error loss function. I also show that by a simple rescaling of the graph's axes, graphical areas are created which can be interpreted as risk under bounded squared-error loss. The bounded loss functions are applied to compare graphically and numerically the risk of exact distributions of the limited-information maximum likelihood and two-stage least-squares estimators in a simultaneous equations model.
Estimation in the Cox-Ingersoll-Ross Model
Authors: Overbeck Ludger , Rydén Tobias
Published: March 2009

The Cox-Ingersoll-Ross model is a diffusion process suitable for modeling the term structure of interest rates. In this paper, we consider estimation of the parameters of this process from observations at equidistant time points. We study two estimators based on conditional least squares as well as a one-step improvement of these, two weighted conditional least-squares estimators, and the maximum likelihood estimator. Asymptotic properties of the various estimators are discussed, and we also compare their performance in a simulation study.
Principal Components Analysis of Cointegrated Time Series
Authors: Harris David
Published: March 2009

This paper considers the analysis of cointegrated time series using principal components methods. These methods have the advantage of requiring neither the normalization imposed by the triangular error correction model nor the specification of a finite-order vector autoregression. An asymptotically efficient estimator of the cointegrating vectors is given, along with tests forcointegration and tests of certain linear restrictions on the cointegrating vectors. An illustrative application is provided.
Valid Edgeworth Expansions of M-Estimators in Regression Models with Weakly Dependent Resfduals
Authors: Taniguchi Masanobu , Puri Madan L.
Published: March 2009

Consider a linear regression model y1 = x1β + u1, where the u1'S afe weakly dependent random variables, the x1's are known design nonrandom variables, and β is an unknown parameter. We define an M-estimator βn of) β corresponding to a smooth score function. Then, the second-order Edgeworth expansion for βn is derived. Here we do not assume the normality of (u1), and (u1) includes the usual ARMA processes. Second, we give the second-order Edgeworth expansion for a transformation T(βn) of βn. Then, a sufficient condition for T to extinguish the second-order terms is given. The results are applicable to many statistical problems.
Stochastic Equicontinuity for Unbounded Dependent Heterogeneous Arrays
Authors: Hansen Bruce E.
Published: March 2009

This paper establishes stochastic equicontinuity for classes of mixingales. Attention is restricted to Lipschitz-continuous parametric functions. Unlike some other empirical process theory for dependent data, our results do not require bounded functions, stationary processes, or restrictive dependence conditions. Applications are given to martingale difference arrays, strong mixing arrays, and near-epoch dependent arrays.
Gaussian Estimation of a Continuous Time Dynamic Model with Common Stochastic Trends
Authors: Simos Theodore
Published: March 2009

We derive the exact discrete model and the Gaussian likelihood function of a first-order system of linear stochastic differential equations driven by an observable vector of stochastic trends and a vector of stationary innovations.
Calculating the Distribution of the Serial Correlation Estimator by Saddlepoint Integration
Authors: Helstrom Carl W.
Published: March 2009

The efficient method of numerical saddlepoint integration is described and applied to calculating the probability distribution of the maximum likelihood and Yule-Walker estimators of the correlation coefficient a of a first-order autoregressive normal time series with initial value either zero or nonzero when a finite number n of data are at hand. Stationary time series of the same type are also treated. Significance points are computed in a number of examples to show how, as n increases, the finite-sample distributions approach the asymptotic distributions that have appeared in the literature.
Using Bootstrapped Confidence Intervals for Improved Inferences with Seemingly Unrelated Regression Equations
Authors: Rilstone Paul , Veall Michael
Published: March 2009

The usual standard errors for the regression coefficients in a seemingly unrelated regression model have a substantial downward bias. Bootstrapping the standard errors does not seem to improve inferences. In this paper, Monte Carlo evidence is reported which indicates that bootstrapping can result in substantially better inferences when applied to t-ratios rather than to standard errors.
Modeling Stock Prices without Knowing How to Induce Stationarity
Authors: Dejong David N. , Whiteman Charles H.
Published: March 2009

In “Modeling Stock Prices without Knowing How to Induce Stationarity” (1994, Econometric Theory 10, 701–719), we used posterior-odds calculations to evaluate restrictions imposed by a present-value model of stock prices across the equations of a VAR representation of stock prices and dividends. The results we reported are tainted by the omission of two factors: the Jacobians induced by the mapping of our priors over VAR parameters β into the restricted sample spaces relevant under hypotheses H2-H4 (hence, tainting our calculations of p(Hi|y,X) in (22) for i = 2–4), and an integrating constant needed in calculating the unrestricted probability p(Hi|y,X) in (22). Table 1 reports our revised calculations, which differ substantively from those reported previously.
Infinite-Order Cointegrated Vector Autoregressive Processes
Authors: Saikkonen Pentti , Lütkepohl HELMUT
Published: March 2009

Estimation of cointegrated systems via autoregressive approximation is considered in the framework developed by Saikkonen (1992, Econometric Theory 8, 1-27). The asymptotic properties of the estimated coefficients of the autoregressive error correction model (ECM) and the pure vector autoregressive (VAR) representations are derived under the assumption that the autoregressive order goes to infinity with the sample size. These coefficients are often used for analyzing the relationships between the variables; therefore, they are important for applied work. Tests for linear restrictions on the coefficients of both the ECM and the pure VAR representation are considered under the present assumptions. It is found that they have limiting x2 distributions. Tests are also derived under the assumption that the number of restrictions goes to infinity with the sample size.
An Alternative Approach to the Asymptotic Theory of Spurious Regression, Cointegration, and Near Cointegration
Authors: Tanaka Katsuto
Published: March 2009

An alternative approach is taken to the asymptotic theory of cointegration. The present approach gives a different expression for the limiting distributions of statistics associated with cointegration, which enables us to compute accurately the distribution functions. Alternative interpretations of cointegration are given and a notion of near cointegration is introduced. We then devise tests which take cointegration as the null and discuss the limiting local power under the alternative of near cointegration.