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Metaanalysis A metaanalysis is a statistical analysis that combines the results of multiple scientific studies. The basic tenet behind metaanalyses is that there is a common truth behind all conceptually similar scientific studies, but which has been measured with a certain error within individual studies. The aim then is to use approaches from statistics to derive a pooled estimate closest to the unknown common truth based on how this error is perceived. In essence, all existing methods yield a weighted average from the results of the individual studies and what differs is the manner in which these weights are allocated and also the manner in which the uncertainty is computed around the point estimate thus generated [...More...]  "Metaanalysis" on: Wikipedia Yahoo 

Crossvalidation (statistics) Crossvalidation, sometimes called rotation estimation,[1][2][3] is a model validation technique for assessing how the results of a statistical analysis will generalize to an independent data set [...More...]  "Crossvalidation (statistics)" on: Wikipedia Yahoo 

Statistically Insignificant In statistical hypothesis testing,[1][2] a result has statistical significance when it is very unlikely to have occurred given the null hypothesis.[3] More precisely, a study's defined significance level, α, is the probability of the study rejecting the null hypothesis, given that it were true;[4] and the pvalue of a result, p, is the probability of obtaining a result at least as extreme, given that the null hypothesis were true [...More...]  "Statistically Insignificant" on: Wikipedia Yahoo 

Receiver Operating Characteristic In statistics, a receiver operating characteristic curve, i.e. ROC curve, is a graphical plot that illustrates the diagnostic ability of a binary classifier system as its discrimination threshold is varied. The ROC curve ROC curve is created by plotting the true positive rate (TPR) against the false positive rate (FPR) at various threshold settings. The truepositive rate is also known as sensitivity, recall or probability of detection[1] in machine learning. The falsepositive rate is also known as the fallout or probability of false alarm[1] and can be calculated as (1 − specificity). It can also be thought of as a plot of the Power as a function of the Type I Error of the decision rule (when the performance is calculated from just a sample of the population, it can be thought of as estimators of these quantities). The ROC curve ROC curve is thus the sensitivity as a function of fallout [...More...]  "Receiver Operating Characteristic" on: Wikipedia Yahoo 

Markov Chain Monte Carlo In statistics, Markov chain Markov chain Monte Carlo (MCMC) methods comprise a class of algorithms for sampling from a probability distribution. By constructing a Markov chain Markov chain that has the desired distribution as its equilibrium distribution, one can obtain a sample of the desired distribution by observing the chain after a number of steps. The more steps there are, the more closely the distribution of the sample matches the actual desired distribution.Convergence of the MetropolisHastings algorithm [...More...]  "Markov Chain Monte Carlo" on: Wikipedia Yahoo 

Statistical Model A statistical model is a mathematical model that embodies a set of statistical assumptions concerning the generation of some sample data and similar data from a larger population. A statistical model represents, often in considerably idealized form, the datagenerating process. The assumptions embodied by a statistical model describe a set of probability distributions, some of which are assumed to adequately approximate the distribution from which a particular data set is sampled. The probability distributions inherent in statistical models are what distinguishes statistical models from other, nonstatistical, mathematical models. A statistical model is usually specified by mathematical equations that relate one or more random variables and possibly other nonrandom variables [...More...]  "Statistical Model" on: Wikipedia Yahoo 

Environmental Protection Agency The United States United States Environmental Protection Agency (EPA or sometimes U.S. EPA) is an agency of the federal government of the United States which was created for the purpose of protecting human health and the environment by writing and enforcing regulations based on laws passed by Congress.[2] President Richard Nixon Richard Nixon proposed the establishment of EPA and it began operation on December 2, 1970, after Nixon signed an executive order. The order establishing the EPA was ratified by committee hearings in the House and Senate. The agency is led by its Administrator, who is appointed by the President and approved by Congress. The current Administrator is Scott Pruitt [...More...]  "Environmental Protection Agency" on: Wikipedia Yahoo 

Cherry Picking (fallacy) Cherry Cherry picking, suppressing evidence, or the fallacy of incomplete evidence is the act of pointing to individual cases or data that seem to confirm a particular position while ignoring a significant portion of related cases or data that may contradict that position. It is a kind of fallacy of selective attention, the most common example of which is the confirmation bias.[1][2] Cherry Cherry picking may be committed intentionally or unintentionally. This fallacy is a major problem in public debate.[3] The term is based on the perceived process of harvesting fruit, such as cherries. The picker would be expected to only select the ripest and healthiest fruits. An observer who only sees the selected fruit may thus wrongly conclude that most, or even all, of the tree's fruit is in a likewise good condition [...More...]  "Cherry Picking (fallacy)" on: Wikipedia Yahoo 

Bias Bias Bias is prejudice in favour of or against one thing, person, or group compared with another, usually in a way considered to be unfair. Biases can be learned implicitly within cultural contexts. People may develop biases toward or against an individual, an ethnic group, a sexual or gender identity, a nation, a religion, a social class, a political party, theoretical paradigms and ideologies within academic domains, or a species.[1] Biased means onesided, lacking a neutral viewpoint, or not having an open mind. Bias Bias can come in many forms and is related to prejudice and intuition.[2] In science and engineering, a bias is a systematic error [...More...]  "Bias" on: Wikipedia Yahoo 

Legislation Legislation (or "statutory law") is law which has been promulgated (or "enacted") by a legislature or other governing body or the process of making it.[1] Before an item of legislation becomes law it may be known as a bill, and may be broadly referred to as "legislation", while it remains under consideration to distinguish it from other business. Legislation can have many purposes: to regulate, to authorize, to outlaw, to provide (funds), to sanction, to grant, to declare or to restrict. It may be contrasted with a nonlegislative act which is adopted by an executive or administrative body under the authority of a legislative act or for implementing a legislative act.[2] Under the Westminster system, an item of primary legislation is known as an Act of Parliament Act of Parliament after enactment. Legislation is usually proposed by a member of the legislature (e.g [...More...]  "Legislation" on: Wikipedia Yahoo 

Political Politics Politics (from Greek: πολιτικά, translit. Politiká, meaning "affairs of the cities") is the process of making decisions that apply to members of a group.[1] It refers to achieving and exercising positions of governance—organized control over a human community, particularly a state.[2] In modern nation states, people have formed political parties to represent their ideas. They agree to take the same position on many issues, and agree to support the same changes to law and the same leaders.[3] An election is usually a competition between different parties.[4] Some examples of political parties are the African National Congress (ANC) in South Africa, the Tories Tories in Great Britain Great Britain and the Indian National Congress. Politics Politics is a multifaceted word [...More...]  "Political" on: Wikipedia Yahoo 

Social Issues A social issue is a problem that influences a considerable number of the individuals within a society. It is often the consequence of factors extending beyond an individual's control, and is the source of a conflicting opinion on the grounds of what is perceived as a morally just personal life or societal order.[clarification needed] Social issues are distinguished from economic issues; however, some issues (such as immigration) have both social and economic aspects. There are also issues that don't fall into either category, such as warfare. There can be disagreements about what social issues are worth solving, or which should take precedence. Different individuals and different societies have different perceptions. In Rights of Man Rights of Man and Common Sense, Thomas Paine Thomas Paine addresses individual's duty to "allow the same rights to others as we allow ourselves" [...More...]  "Social Issues" on: Wikipedia Yahoo 

Economic An economy (from Greek οίκος – "household" and νέμoμαι – "manage") is an area of the production, distribution, or trade[1], and consumption of goods and services by different agents. Understood in its broadest sense, 'The economy is defined as a social domain that emphasizes the practices, discourses, and material expressions associated with the production, use, and management of resources'.[2] Economic agents can be individuals, businesses, organizations, or governments. Economic transactions occur when two parties agree to the value or price of the transacted good or service, commonly expressed in a certain currency. However, monetary transactions only account for a small part of the economic domain. Economic activity is spurred by production which uses natural resources, labor, and capital [...More...]  "Economic" on: Wikipedia Yahoo 

Imputation (statistics) In statistics, imputation is the process of replacing missing data with substituted values. When substituting for a data point, it is known as "unit imputation"; when substituting for a component of a data point, it is known as "item imputation". There are three main problems that missing data causes: missing data can introduce a substantial amount of bias, make the handling and analysis of the data more arduous, and create reductions in efficiency.[1] Because missing data can create problems for analyzing data, imputation is seen as a way to avoid pitfalls involved with listwise deletion of cases that have missing values. That is to say, when one or more values are missing for a case, most statistical packages default to discarding any case that has a missing value, which may introduce bias or affect the representativeness of the results. Imputation preserves all cases by replacing missing data with an estimated value based on other available information [...More...]  "Imputation (statistics)" on: Wikipedia Yahoo 

Maximum Likelihood Estimation In statistics, maximum likelihood estimation (MLE) is a method of estimating the parameters of a statistical model, given observations. MLE attempts to find the parameter values that maximize the likelihood function, given the observations. The resulting estimate is called a maximum likelihood estimate, which is also abbreviated as MLE. The method of maximum likelihood is used with a wide range of statistical analyses. As an example, suppose that we are interested in the heights of adult female penguins, but are unable to measure the height of every penguin in a population (due to cost or time constraints). Assuming that the heights are normally distributed with some unknown mean and variance, the mean and variance can be estimated with MLE while only knowing the heights of some sample of the overall population [...More...]  "Maximum Likelihood Estimation" on: Wikipedia Yahoo 

Base Rate Fallacy The base rate fallacy, also called base rate neglect or base rate bias, is a formal fallacy. If presented with related base rate information (i.e. generic, general information) and specific information (information pertaining only to a certain case), the mind tends to ignore the former and focus on the latter.[1] Base rate neglect is a specific form of the more general extension neglect.Contents1 Examples1.1 Example 1: Drunk drivers 1.2 Example 2: Terrorist identification2 Findings in psychology 3 See also 4 References 5 External linksExamples[edit] Example 1: Drunk drivers[edit]A group of police officers have breathalyzers displaying false drunkenness in 5% of the cases in which the driver is sober. However, the breathalyzers never fail to detect a truly drunk person. One in a thousand drivers is driving drunk. Suppose the police officers then stop a driver at random, and force the driver to take a breathalyzer test. It indicates that the driver is drunk [...More...]  "Base Rate Fallacy" on: Wikipedia Yahoo 