Search results for "Selection bia"
showing 10 items of 50 documents
Tranexamic acid for trauma
2010
What Do We Know About the Second Moment of Financial Markets?
2021
Recent research shows that the vast majority of scientific studies published in leading finance journals fails scientific replication (Hou, Xue, and Zhang, 2020; Harvey, Liu, and Zhu; 2016). This study argues that p-hacking, publication pressure and the selection bias from leading finance journals are perhaps not the underlying root cause for this issue. We show that standard methodologies often used in finance research are inevitably sample-specific due to the very nature of financial markets. While the consensus of earlier research postulates a rejection of the time-honored Levy hypothesis, our results strongly indicate that the variance of variance does not exist in any of the financial …
Am I riskier if I rescue my banks? Beyond the effects of bailouts
2021
Abstract We examine the relationship between bank bailouts and sovereign risk in 35 countries and 19 bailouts from 2005 to 2015. Bailouts negatively affect sovereign ratings, with rating agencies consistently perceiving higher risk when a country’s banking system has been rescued (risk-increasing effect). The increase in public debt as a result of the bank bailouts is the main mechanism through which the risk-increasing effect occurs. Moreover, financial soundness and banking market structure shape the impact of bailouts on sovereign risk. In particular, proactiveness in undertaking public bailouts for banking systems that are largely distressed – that is, risky and low profitable – and hig…
Am I riskier if I rescue my banks? The unintended effects of bailouts
2021
We examine the relationship between bank bailouts and sovereign risk in 35 countries and 19 bailouts during 2005–2015. Bailouts negatively affect sovereign ratings, with rating agencies consistently perceiving higher risk when the country’s banking system has been rescued (risk-increasing effect). Financial soundness and banking market structure shape the impact of bailouts on sovereign risk. In particular, proactiveness in undertaking public bailouts for banking systems that are largely distressed -risky and low profitable- and highly concentrated seems to lead to lower increases in sovereign risk. However, the strength of the connection between the public sector and the banking system nei…
Estimating the non-market benefits of water quality improvement for a case study in Spain: A contingent valuation approach
2012
Abstract This article addresses an important topic related to the application of the European Water Framework Directive (WFD) in Spanish watersheds. Results on a contingent valuation study, aimed to assess the non-market benefits of water quality improvements in the Guadiana river basin (GRB), are shown. Special attention has been paid to the issue of zero willingness-to-pay (WTP) responses, while addressing the possible presence of self-selection caused by protest responses. The results (i) indicate that sample selection bias is not a problem in our application, (ii) allow us to identify some key determinants of voting behaviour, and (iii) through the use of different econometric models al…
Le score de propension : un guide méthodologique pour les recherches expérimentales et quasi expérimentales en éducation
2016
La méthode du score de propension devient de plus en plus populaire pour estimer les effets causaux d’un programme d’intervention. Si les applications empiriques de cette méthode sont encore rares dans les recherches en éducation, des exemples de son utilisation se trouvent aisément dans d’autres disciplines. Cependant, sa mise en place soulève plusieurs questions. L’objectif de cet article est de fournir des éléments de réponses guidant le chercheur et l’évaluateur du domaine de l’éducation pour l’estimation et l’utilisation du score de propension. Les différentes étapes de son application sont présentées pas à pas : évaluation du biais de sélection, construction du score de propension et …
Financial Aspects of Cervical Disc Arthroplasty: A Narrative Review of Recent Literature
2020
Recently, there has been significant interest in understanding the cost-effectiveness of treatments in spine surgery as health care systems in the United States move toward value-based care and alternative payment models. Previous studies have shown comparable outcomes of cervical disc arthroplasty (CDA) and anterior cervical discectomy fusion; however, there is a lack of consensus on the cost-effectiveness of CDA to support full adoption. Evidence of the limitations of these cost-analysis studies also exists in the literature, including industry funding, potential selection bias, and varying methods of calculating value. The goal of this narrative review is to provide an overview of the co…
Methodology for high-quality studies on course and prognosis of inflammatory bowel disease.
2012
Inflammatory bowel diseases (IBDs) are characterized by a chronic course with an alternation of relapses and remissions. Questions about prognosis are important for the patient who wants to know how the disease will affect his/her life and also for clinicians to make management decisions. Correct selection of the patients is the basis for good methodological studies on the course of IBD. A great proportion of data on the course of IBD is derived from a limited number of cohort studies. Studies help to define the endpoints for clinical trials and to identify subsets of patients in whom the prognosis of the disease can be stratified according to clinical features. Specific scientific requirem…
An examination of nonresponse in a study on daily family life: I do not have time to participate, but I can tell you something about our life
2012
The aim of this study was to look at the issue of nonresponse and self-selection bias in the context of a family study on daily family life. Data on the participating families and refusers were gathered as part of the wider Palette study in which questionnaires and diaries were used as data collection methods. On the basis of these data (N = 208 participating families and 119 refuser families), we profile the families left outside the study. The parents who declined to participate in the Palette study were asked to fill in a short refusal form, which included questions concerning their family background and reasons for refusal, and they were also asked to write freely about their everyday l…
Statistical modelling of selective non-participation in health examination surveys
2018
Health examination surveys aim to collect reliable information on the health and risk factors of a population of interest. Missing data occur when some invitees do not participate the survey. If non-participation is associated with the variables to be studied, then the estimates based only on the participants cannot be generalised to the population of interest. In this case, the estimates have selection bias, which misleads the decision-makers. The purpose of this thesis is to develop statistical methods to reduce the selection bias in the cross-sectional data using additional data sources. The data, which we use, comes from the National FINRISK Study, and we aim to estimate the prevalences…