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Subgroup Analysis
Subgroup analysis refers to repeating the analysis of a study within subgroups of subjects defined by a subgrouping variable (e.g. smoking status defining two subgroups: smokers and non-smokers). Aim The aim of subgroup analysis is usually to assess whether the association of two variables differs depending on a third variable. For instance, investigators of a study testing the effect of an intervention (variable 1) on preventing heart attacks (variable 2) might be interested in whether the effect varies by smoking status (variable 3). Therefore, they could perform separate analyses for smokers and non-smokers, and then compare the results. If results differ, there is a subgroup effect. Terminology The terminology is inconsistent. Alternative names for subgrouping variables include effect modifiers, predictive factors, or moderators. Alternative names for subgroup effects include effect modification and interaction. Some authors define effect modification and interaction differe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NEJM
''The New England Journal of Medicine'' (''NEJM'') is a weekly medical journal published by the Massachusetts Medical Society. It is among the most prestigious peer-reviewed medical journals as well as the oldest continuously published one. History In September 1811, John Collins Warren, a Boston physician, along with James Jackson, submitted a formal prospectus to establish the ''New England Journal of Medicine and Surgery and Collateral Branches of Science'' as a medical and philosophical journal. Subsequently, the first issue of the ''New England Journal of Medicine and Surgery and the Collateral Branches of Medical Science'' was published in January 1812. The journal was published quarterly. In 1823, another publication, the ''Boston Medical Intelligencer'', appeared under the editorship of Jerome V. C. Smith. The editors of the ''New England Journal of Medicine and Surgery and the Collateral Branches of Medical Science'' purchased the weekly ''Intelligencer'' for $600 in 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart Attack
A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may travel into the shoulder, arm, back, neck or jaw. Often it occurs in the center or left side of the chest and lasts for more than a few minutes. The discomfort may occasionally feel like heartburn. Other symptoms may include shortness of breath, nausea, feeling faint, a cold sweat or feeling tired. About 30% of people have atypical symptoms. Women more often present without chest pain and instead have neck pain, arm pain or feel tired. Among those over 75 years old, about 5% have had an MI with little or no history of symptoms. An MI may cause heart failure, an irregular heartbeat, cardiogenic shock or cardiac arrest. Most MIs occur due to coronary artery disease. Risk factors include high blood pressure, smoking, diabetes, lack of e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Post-hoc Analysis
In a scientific study, post hoc analysis (from Latin '' post hoc'', "after this") consists of statistical analyses that were specified after the data were seen. They are usually used to uncover specific differences between three or more group means when an analysis of variance (ANOVA) test is significant. This typically creates a multiple testing problem because each potential analysis is effectively a statistical test. Multiple testing procedures are sometimes used to compensate, but that is often difficult or impossible to do precisely. Post hoc analysis that is conducted and interpreted without adequate consideration of this problem is sometimes called ''data dredging'' by critics because the statistical associations that it finds are often spurious. Common post hoc tests Some common post hoc tests include: {{Cite web , last=Pamplona , first=Fabricio , date=2022-07-28 , title=Post Hoc Analysis: Process and types of tests , url=https://mindthegraph.com/blog/post-hoc-analysis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statistical Analysis
Statistical inference is the process of using data analysis to infer properties of an underlying distribution of probability.Upton, G., Cook, I. (2008) ''Oxford Dictionary of Statistics'', OUP. . Inferential statistical analysis infers properties of a population, for example by testing hypotheses and deriving estimates. It is assumed that the observed data set is sampled from a larger population. Inferential statistics can be contrasted with descriptive statistics. Descriptive statistics is solely concerned with properties of the observed data, and it does not rest on the assumption that the data come from a larger population. In machine learning, the term ''inference'' is sometimes used instead to mean "make a prediction, by evaluating an already trained model"; in this context inferring properties of the model is referred to as ''training'' or ''learning'' (rather than ''inference''), and using a model for prediction is referred to as ''inference'' (instead of ''prediction''); ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Design Of Experiments
The design of experiments (DOE, DOX, or experimental design) is the design of any task that aims to describe and explain the variation of information under conditions that are hypothesized to reflect the variation. The term is generally associated with experiments in which the design introduces conditions that directly affect the variation, but may also refer to the design of quasi-experiments, in which natural conditions that influence the variation are selected for observation. In its simplest form, an experiment aims at predicting the outcome by introducing a change of the preconditions, which is represented by one or more independent variables, also referred to as "input variables" or "predictor variables." The change in one or more independent variables is generally hypothesized to result in a change in one or more dependent variables, also referred to as "output variables" or "response variables." The experimental design may also identify control variables that must be h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
