Search results for "Selection bias"
showing 10 items of 49 documents
Effectiveness of child protection practice models : a systematic review
2020
Background Attempts to improve child protection outcomes by implementing social work practice models embedded in a particular theory and practice approach, have increased internationally over the past decade. Objective To assess the evidence of the effectiveness of child protection practice models in improving outcomes for children and families. Participants and setting Children < 18 years and their families involved in child protection services. Methods A systematic review was conducted to synthesize evidence regarding the effectiveness of child protection practice models. Systematic searches across 10 electronic databases and grey literature were conducted to identify quasi-experimental s…
Vasopressor and inotrope treatment for septic shock: An umbrella review of reviews
2021
Abstract Purpose To review the characteristics, findings and quality of systematic reviews (SRs) on the effect of any vasopressor/inotrope on outcomes in adult patients with sepsis compared with either no treatment, another vasopressor or inotrope or fluids. Materials and methods We systematically searched Cochrane Central Register of Controlled Trials, PubMed and Embase (January 1993–March 2021). Descriptive statistics were used. Results Among the 28 SRs identified, mortality was the primary outcome in most (26/28) and mortality was usually (23/28) studied using randomised controlled trials (RCTs). Fifteen SRs focused exclusively on patients with sepsis or septic shock. Sepsis and septic s…
Familial HDL deficiency due to ABCA1 gene mutations with or without other genetic lipoprotein disorders
2004
Mutations in ABCA1 have been shown to be the cause of Tangier disease (TD) and some forms of familial hypoalphalipoproteinemia (HA), two genetic disorders characterized by low plasma HDL levels. Here we report six subjects with low HDL, carrying seven ABCA1 mutations, six of which are previously unreported. Two mutations (R557X and H160FsX173) were predicted to generate short truncated proteins; two mutations (E284K and Y482C) were located in the first extracellular loop and two (R1901S and Q2196H) in the C-terminal cytoplasmic domain of ABCA1. Two subjects found to be compound heterozygotes for ABCA1 mutations did not have overt clinical manifestations of TD. Three subjects, all with prema…
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…
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…
Are private schools more efficient than public schools ? Evidence from Tanzania
2001
International audience; Beginning in the mid-1980s, there has been an explosive growth of private secondary schools in Tanzania. By easing constraints on private operators, the government has clearly found an effective way in the context of right public budget constraints to cope with the excess demand for this level of schooling. But has the policy also led to efficient operations in terms of student learning ? In this paper, we attempt to shed light on this issue by comparing the efficiency of four types of schools that make up the majority of schools in the country : Government and Community schools in the public sector, and Chirstian and Wazazi schools in the private sector. Using longi…
Estimation de la relation de salaires de Mincer : choix de specification et enjeux économétriques
2012
In the present doctoral thesis, we estimated Mincer’s (1974) semi logarithmic wage function for the French and Pakistani labour force data. This model is considered as a standard tool in order to estimate the relationship between earnings/wages and different contributory factors. Despite of its vide and extensive use, simple estimation of the Mincerian model is biased because of different econometric problems. The main sources of bias noted in the literature are endogeneity of schooling, measurement error, and sample selectivity. We have tackled the endogeneity and measurement error biases via instrumental variables two stage least squares approach for which we have proposed two new instrum…
Robust Estimation of Infection Fatality Rates during the Early Phase of a Pandemic
2020
AbstractDuring a pandemic, robust estimation of case fatality rates (CFRs) is essential to plan and control suppression and mitigation strategies. At present, estimates for the CFR of COVID-19 caused by SARS-CoV-2 infection vary considerably. Expert consensus of 0.1–1% covers in practical terms a range from normal seasonable Influenza to Spanish Influenza. In the following, I deduce a formula for an adjusted Infection Fatality Rate (IFR) to assess mortality in a period following a positive test adjusted for selection bias.Official datasets on cases and deaths were combined with data sets on number of tests. After data curation and quality control, a total of IFR (n=819) was calculated for 2…
Do-search -- a tool for causal inference and study design with multiple data sources
2020
Epidemiologic evidence is based on multiple data sources including clinical trials, cohort studies, surveys, registries, and expert opinions. Merging information from different sources opens up new possibilities for the estimation of causal effects. We show how causal effects can be identified and estimated by combining experiments and observations in real and realistic scenarios. As a new tool, we present do-search, a recently developed algorithmic approach that can determine the identifiability of a causal effect. The approach is based on do-calculus, and it can utilize data with nontrivial missing data and selection bias mechanisms. When the effect is identifiable, do-search outputs an i…
Causal Effect Identification from Multiple Incomplete Data Sources: A General Search-Based Approach
2021
Causal effect identification considers whether an interventional probability distribution can be uniquely determined without parametric assumptions from measured source distributions and structural knowledge on the generating system. While complete graphical criteria and procedures exist for many identification problems, there are still challenging but important extensions that have not been considered in the literature. To tackle these new settings, we present a search algorithm directly over the rules of do-calculus. Due to generality of do-calculus, the search is capable of taking more advanced data-generating mechanisms into account along with an arbitrary type of both observational and…