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Uncertainty Coefficient
In statistics, the uncertainty coefficient, also called proficiency, entropy coefficient or Theil's U, is a measure of nominal association. It was first introduced by Henri Theil and is based on the concept of information entropy. Definition Suppose we have samples of two discrete random variables, ''X'' and ''Y''. By constructing the joint distribution, , from which we can calculate the conditional distributions, and , and calculating the various entropies, we can determine the degree of association between the two variables. The entropy of a single distribution is given as: : H(X)= -\sum_x P_X(x) \log P_X(x) , while the conditional entropy is given as: : H(X, Y) = -\sum_ P_(x,~y) \log P_(x, y) . The uncertainty coefficient or proficiency is defined as: : U(X, Y) = \frac = \frac , and tells us: given ''Y'', what fraction of the bits of ''X'' can we predict? In this case we can think of ''X'' as containing the total information, and of ''Y'' as allowing one to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statistics
Statistics (from German: '' Statistik'', "description of a state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a scientific, industrial, or social problem, it is conventional to begin with a statistical population or a statistical model to be studied. Populations can be diverse groups of people or objects such as "all people living in a country" or "every atom composing a crystal". Statistics deals with every aspect of data, including the planning of data collection in terms of the design of surveys and experiments.Dodge, Y. (2006) ''The Oxford Dictionary of Statistical Terms'', Oxford University Press. When census data cannot be collected, statisticians collect data by developing specific experiment designs and survey samples. Representative sampling assures that inferences and conclusions can reasonably extend from the sample to the population as a whole. An ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Density Estimation
In statistics, probability density estimation or simply density estimation is the construction of an estimate, based on observed data, of an unobservable underlying probability density function. The unobservable density function is thought of as the density according to which a large population is distributed; the data are usually thought of as a random sample from that population. A variety of approaches to density estimation are used, including Parzen windows and a range of data clustering techniques, including vector quantization. The most basic form of density estimation is a rescaled histogram. Example We will consider records of the incidence of diabetes. The following is quoted verbatim from the data set description: :''A population of women who were at least 21 years old, of Pima Indian heritage and living near Phoenix, Arizona, was tested for diabetes mellitus according to World Health Organization criteria. The data were collected by the US Nation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Summary Statistics For Contingency Tables
may refer to: * Abstract (summary), shortening a passage or a write-up without changing its meaning but by using different words and sentences * Epitome, a summary or miniature form * Abridgement, the act of reducing a written work into a shorter form * Summary or executive summary of a document, a short document or section that summarizes a longer document such as a report or proposal or a group of related reports * Introduction (writing) * Summary (law), which has several meanings in law * Automatic summarization, the use of a computer program to produce an abstract or abridgement * Synopsis (other) A synopsis is a brief summary of the major points of a subject or written work or story, either as prose or as a table; an abridgment or condensation of a work. Synopsis or synopsys may also refer to: * Video synopsis, an approach to create a sho ... * Overview (other) {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statistical Ratios
Statistics (from German: '' Statistik'', "description of a state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a scientific, industrial, or social problem, it is conventional to begin with a statistical population or a statistical model to be studied. Populations can be diverse groups of people or objects such as "all people living in a country" or "every atom composing a crystal". Statistics deals with every aspect of data, including the planning of data collection in terms of the design of surveys and experiments.Dodge, Y. (2006) ''The Oxford Dictionary of Statistical Terms'', Oxford University Press. When census data cannot be collected, statisticians collect data by developing specific experiment designs and survey samples. Representative sampling assures that inferences and conclusions can reasonably extend from the sample to the population as a whole. An exper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary Classification
Binary classification is the task of classifying the elements of a set into two groups (each called ''class'') on the basis of a classification rule. Typical binary classification problems include: * Medical testing to determine if a patient has certain disease or not; * Quality control in industry, deciding whether a specification has been met; * In information retrieval, deciding whether a page should be in the result set of a search or not. Binary classification is dichotomization applied to a practical situation. In many practical binary classification problems, the two groups are not symmetric, and rather than overall accuracy, the relative proportion of different types of errors is of interest. For example, in medical testing, detecting a disease when it is not present (a ''false positive'') is considered differently from not detecting a disease when it is present (a '' false negative''). Statistical binary classification Statistical classification is a problem stud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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