Search results for "selection bias."
showing 10 items of 49 documents
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…
Lost to follow-up in the Norwegian mother, father and child cohort study.
2021
Background The aim of pregnancy cohorts was to understand causes and development of health and disease throughout the life course. A major challenge in cohort studies is to avoid selection bias from loss to follow-up. Objective The aim of this study was to describe what characterises drop out from the Norwegian Mother, Father and Child Cohort Study (MoBa), and provide a resource to inform the interpretation of results from analysis of cohort data. Methods We estimated loss to follow-up in subsets of participants that responded to questionnaire waves in MoBa through an eight-year period and described characteristics of participants who responded to follow-ups. Within each wave of questionnai…
Self-reported health versus biomarkers: does unemployment lead to worse health?
2020
Abstract Objectives This paper examines the relationship between unemployment and health using both subjective and biometric information on health status. Study design Longitudinal panel data. Methods We compare the results of regressions of unemployment on self-reported health with those of regressions of unemployment on health as measured with biomarkers (hypertension and levels of blood glucose and C-reactive protein). Using the panel structure of our data, we account for selection bias with respect to unemployment by controlling for health before exposure to unemployment. Results We observe a striking pattern. Using self-reported health as the outcome variable, we find a link between un…
Hospital readmission rates: signal of failure or success?
2013
AbstractHospital readmission rates are increasingly used as signals of hospital performance and a basis for hospital reimbursement. However, their interpretation may be complicated by differential patient survival rates. If patient characteristics are not perfectly observable and hospitals differ in their mortality rates, then hospitals with low mortality rates are likely to have a larger share of un-observably sicker patients at risk of a readmission. Their performance on readmissions will then be underestimated. We examine hospitals’ performance relaxing the assumption of independence between mortality and readmissions implicitly adopted in many empirical applications. We use data from th…
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 …
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…
Recommendations for design and analysis of health examination surveys under selective non-participation
2019
Background The decreasing participation rates and selective non-participation peril the representativeness of health examination surveys (HESs). Methods Finnish HESs conducted in 1972–2012 are used to demonstrate that survey participation rates can be enhanced with well-planned recruitment procedures and auxiliary information about survey non-participants can be used to reduce selection bias. Results Experiments incorporated to pilot surveys and experience from previously conducted surveys lead to practical improvements. For example, SMS reminders were taken as a routine procedure to the Finnish HESs after testing their effect on a pilot study and finding them as a cost-effective way to inc…
The financial burden of non-communicable chronic diseases in rural Nigeria: Wealth and gender heterogeneity in health care utilization and health exp…
2016
Objectives Better insights into health care utilization and out-of-pocket expenditures for non-communicable chronic diseases (NCCD) are needed to develop accessible health care and limit the increasing financial burden of NCCDs in Sub-Saharan Africa. Methods A household survey was conducted in rural Kwara State, Nigeria, among 5,761 individuals. Data were obtained using biomedical and socio-economic questionnaires. Health care utilization, NCCD-related health expenditures and distances to health care providers were compared by sex and by wealth quintile, and a Heckman regression model was used to estimate health expenditures taking selection bias in health care utilization into account. Res…
The MOBI-Kids Study Protocol: Challenges in Assessing Childhood and Adolescent Exposure to Electromagnetic Fields from Wireless Telecommunication Tec…
2014
The rapid increase in mobile phone use in young people has generated concern about possible health effects of exposure to radiofrequency (RF) and extremely low frequency (ELF) electromagnetic fields (EMF). MOBI-Kids, a multinational case–control study, investigates the potential effects of childhood and adolescent exposure to EMF from mobile communications technologies on brain tumor risk in 14 countries. The study, which aims to include approximately 1,000 brain tumor cases aged 10–24 years and two individually matched controls for each case, follows a common protocol and builds upon the methodological experience of the INTERPHONE study. The design and conduct of a study on EMF exposure an…
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…