6,052 articles
Extreme value theory
Extreme value theory is the branch of statistics concerned with the limiting behavior of unusually large or small observations, with applications in hydrology and finance.
Extreme-value copula
An extreme-value copula is a copula arising as the weak limit of componentwise maxima of independent samples, equivalently a max-stable copula applied in finance, insurance, and hydrology.
Extrinsic curvature
Extrinsic curvature is the curvature a submanifold has because of how it sits inside an ambient space, unlike intrinsic curvature, which depends only on its own metric.
Eyring equation
The Eyring equation, or Eyring-Polanyi equation, gives a reaction's rate constant from temperature and the activation enthalpy and entropy, developed by Henry Eyring in 1935.
F-algebra
An F-algebra, or algebra for an endofunctor, is a category-theory construction generalizing algebraic structure: a pair (A, α) with α : F(A) → A for an endofunctor F.
F-distribution
The F-distribution, also called Snedecor's F distribution, is a continuous probability distribution of the ratio of two independent chi-squared variables, used in the F-test and ANOVA.
F-score
The F-score, also called the F-measure or F1 score, is a performance metric for binary classification and information retrieval that combines precision and recall as their harmonic mean.
F-test
The F-test is a hypothesis test whose statistic follows the F distribution and is a ratio of two variances, used to compare two variances or several means in ANOVA.
F4 Lie algebra
F4 is one of the five exceptional simple Lie algebras, a 52-dimensional complex simple Lie algebra of rank 4 whose root system has two root lengths, classified by Killing and Cartan.
Facility location problem
The facility location problem (FLP) is an optimization problem that determines the best placement of facilities such as warehouses or hospitals, balancing facility opening costs against transportation costs.
Factor analysis
Factor analysis is a statistical method that explains correlations among observed variables through fewer unobserved factors; invented by Charles Spearman in 1904, it is a core psychometrics tool.
Factor graph
A factor graph is a bipartite graphical model where variable and factor nodes express how a global function of many variables factors into local functions of subsets of variables.
Factor rotation
Factor rotation is a transformation in exploratory factor analysis that reorients the factor axes to reach simple structure, changing nothing about how well the model fits the data.
Factor theorem
The factor theorem is an algebra theorem stating that a number a is a zero of a polynomial f(x) if and only if x − a is a factor.
Factorial
The factorial of a non-negative integer n, written n!, is the product of all integers from n down to 1, so 5! = 120 and 0! = 1.
Factorial design
A factorial design is an experimental design varying two or more factors together so one set of runs estimates each factor's effect and their interactions.
Factorial experiment
A factorial experiment varies several input factors, each at two or more levels, so every combination appears in the plan, estimating both main effects and interactions that one-factor-at-a-time studies miss.
Factorization
Factorization is the decomposition of an element of a ring into a product of simpler elements, generalizing prime factorization of integers; unique factorization domains are where this decomposition is unique.
Factorization of polynomials
Factorization of polynomials is the computation expressing a polynomial as a product of irreducible factors over a given coefficient ring, a central problem in computational algebra.
Factorization of polynomials over finite fields
Factorization of polynomials over finite fields is the task of writing a polynomial over Fq as a product of irreducible polynomials, computed by efficient algorithms.
Fagin's theorem
Fagin's theorem, proved by Ronald Fagin in 1974, states that a property of finite structures is in NP if and only if it is definable in existential second-order logic.
Failure mode and effects analysis
Failure mode and effects analysis (FMEA) is a systematic method for identifying how an item or process might fail, first formalized by the US military in 1949.
Failure rate
Failure rate, also called the hazard rate, is the frequency at which engineered items fail per unit time, the fundamental quantity of reliability engineering for predicting how long systems function.
Faithfully flat descent
Faithfully flat descent is a technique in algebra and algebraic geometry, developed by Grothendieck, for transferring properties from a faithfully flat extension back to the base.
False dilemma
A false dilemma, also called a false dichotomy or either-or fallacy, is an informal fallacy that assumes only two options exist when other alternatives do.
False discovery rate
The false discovery rate (FDR) is an error measure for multiple hypothesis testing: the expected proportion of false positives among rejected hypotheses, formalized by Benjamini and Hochberg in 1995.
False Negative Reactions
False Negative Reactions: MeSH term (D005188) for negative test results in people who have the tested condition; false negative rate = 1 − sensitivity, ranging from 1.5% (myocardial infarction) to 56% (spinal abscess) in ED studies.
False positive rate
The false positive rate (FPR) is the proportion of condition-free subjects that a test or classifier wrongly flags as positive, equal to 1 − specificity.
False positives and false negatives
A false positive is a test result that incorrectly indicates a condition is present, and a false negative one that incorrectly indicates it is absent, measured by sensitivity and specificity.
Falsification test
A falsification test is a statistical and econometric validation procedure that reruns a hypothesis test on placebo data where no true effect should exist, checking for spurious results.