42,772 articles
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.
FactSage
FactSage is a thermochemical software and database package that calculates chemical equilibria, phase equilibria, and phase diagrams in multicomponent systems, introduced in 2001 as the fusion of FACT-Win and ChemSage.
Faddeev equations
The Faddeev equations are three coupled integral equations of quantum mechanics, proposed by Ludvig Faddeev in 1960, that describe the scattering and binding of three interacting particles.
Fading
Fading, also known as amplitude fading, is the fluctuation of a received radio signal's amplitude and phase over time, frequency, or space, caused by multipath propagation.
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.
Fahmi Himo
Fahmi Himo (born 1973) is a Swedish computational chemist and professor of quantum chemistry at Stockholm University, known for the quantum chemical cluster approach to enzyme catalysis.
Fahrenheit
Fahrenheit, also known as the Fahrenheit scale, is a temperature scale proposed in 1724 by Daniel Gabriel Fahrenheit, with water freezing at 32 degrees and boiling at 212.
Failed supernova
A failed supernova, or unnova, is the core collapse of a massive star that forms a black hole without a luminous supernova, so the star vanishes.
Faille
Faille is a ribbed woven fabric, typically light silk; the French word also denotes a geological fault along which rock blocks move, as in earthquakes or creep.
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.
Faint young Sun paradox
The faint young Sun paradox is the conflict between a Sun 20 to 25% fainter on early Earth and geological evidence that liquid water existed.
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.
Falapen (penicillin)
Falapen is a brand name for penicillin G potassium, the potassium salt of benzylpenicillin, a β-lactam antibiotic used against serious bacterial infections like pneumonia, meningitis, and syphilis.
Falkland Islands oil
Falkland Islands oil refers to offshore petroleum resources around the Falkland Islands, where the Sea Lion field, discovered in 2010, is set to produce first oil in 2028.
Fallen Astronaut
Fallen Astronaut is a small aluminum figurine placed on the Moon in 1971 by Apollo 15 commander David Scott, beside a plaque honoring 14 dead astronauts and cosmonauts.
Fallstreak hole
A fallstreak hole, also called a hole punch cloud or skypunch, is a large circular gap in a thin cloud layer of supercooled droplets, usually triggered by aircraft.
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.