نتایج جستجو برای: bias epidemiology
تعداد نتایج: 212315 فیلتر نتایج به سال:
A well-known heuristic in epidemiology is that non-differential exposure or disease misclassification biases the expected values of an estimator toward the null value. This heuristic works correctly only when additional conditions are met, such as independence of classification errors. We present examples to show that, even when the additional conditions are met, if the misclassification is onl...
We propose a class of continuous-time Markov counting processes for analyzing correlated binary data and establish a correspondence between these models and sums of exchangeable Bernoulli random variables. Our approach generalizes many previous models for correlated outcomes, admits easily interpretable parameterizations, allows different cluster sizes, and incorporates ascertainment bias in a ...
Meta-analysis has seen increasing use as a tool in epidemiology over the past five years. Although this method is relatively well accepted for use in clinical trials, its use has proved somewhat more controversial in epidemiology. If meta-analysis is viewed as an evolutionary improvement over the review article, it may become more widely acceptable. Meta-analysis should incorporate the concern ...
BACKGROUND AND OBJECTIVES In many places in Europe, the ambient air pollution exceeds the levels considered to be safe for health. The objective of the paper is to review and summarise the methods of assessment of its impact on health, and to indicate the contributions of various research disciplines, particularly environmental epidemiology. METHODS The framework for assessment of impact is b...
Pharmacovigilance is “the science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other drug related problem”. There is criticism that drug safety reporting in medical research is inadequate. There is possibility of many types of bias in vaccine safety studies especially in the diagnostic process, at investigator level and in the proc...
There are different reasons for the increase in the use of biomarkers in cancer epidemiology which is as follows: (i) the fact that the identification of new carcinogens, characterized by complex exposure circumstances and weak effects, has become increasingly difficult with traditional epidemiological approaches; (ii) the increasing understanding of mechanisms of carcinogenesis and (iii) techn...
In teaching epidemiology, confounding is a difficult topic. The authors designed active learning objects (LO) based on manipulable three-dimensional (3D) plots to facilitate understanding of confounding. The 3D LOs help illustrate of how confounding can occur, how it generates bias and how to adjust for it. For the development of the LOs, guidelines were formulated based on epidemiology and the...
BACKGROUND In addition to acute hospital mortality, sepsis is associated with higher risk of death following hospital discharge. We assessed the strength of epidemiological evidence supporting a causal link between sepsis and mortality after hospital discharge by systematically evaluating the available literature for strength of association, bias, and techniques to address confounding. METHOD...
BACKGROUND Opt-in consent is usually required for research, but is known to introduce selection bias. This is a particular problem for large scale epidemiological studies using only pre-collected health data. Most previous studies have shown that members of the public value opt-in consent and can perceive research without consent as an invasion of privacy. Past research has suggested that peopl...
BACKGROUND Up-to-date identification of local trends in sepsis incidence and outcomes is of considerable public health importance. The aim of our study was to estimate annual incidence rates and in-hospital mortality trends for hospitalized patients with sepsis in a European setting, while avoiding selection bias in relation to different complexity hospitals. METHODS A large retrospective ana...
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