42,772 articles
Random walk
A random walk, also called a drunken walk, is a stochastic process describing a path formed by successive random steps, used to model diffusion and fluctuation.
Random-access machine
A random-access machine (RAM) is an abstract model of computation: a program operating on an array of registers, any of which can be read or written directly by index.
Random-effects meta-analysis
Random-effects meta-analysis is a statistical method for combining effect estimates from multiple studies assumed to vary, following a distribution with a mean and a between-study variance.
Random-field Ising model
The random-field Ising model is a lattice spin model in which ferromagnetic Ising spins couple to frozen random fields, introduced by Imry and Ma in 1975 and central to disordered systems.
Random-matrix theory of quantum transport
Random-matrix theory of quantum transport describes scattering in mesoscopic systems like quantum dots by ensembles of random scattering matrices, yielding universal conductance averages and fluctuations.
Randomization inference
Randomization inference, also known as permutation inference, is a statistical method for testing treatment effects in experiments by computing a test statistic's distribution over all possible random assignments, requiring no distributional assumptions.
Randomization test
A randomization test is a statistical significance test that evaluates a treatment effect by repeatedly reassigning group labels at random, giving exact Type I error control without distributional assumptions.
Randomized benchmarking
Randomized benchmarking is an experimental protocol that estimates the average error rate of quantum gates by fitting how survival probability decays over random gate sequences, avoiding dependence on state preparation and measurement errors.
Randomized block design
A randomized block design is a statistical experimental design that groups similar units into blocks and randomizes treatments within each block, removing block-to-block variation from experimental error.
Randomized compiling
Randomized compiling (RC) is a quantum computing protocol, proposed by Wallman and Emerson in 2015, that inserts random single-qubit gates to turn coherent errors into stochastic Pauli errors.
Randomized experiment
A randomized experiment is a study design in which participants are assigned to treatment or control groups by a random mechanism, allowing causal effects to be estimated.
Randomized rounding
Randomized rounding is a technique in combinatorial optimization that turns a fractional linear programming solution into an integer one, introduced by Raghavan and Thompson in 1987.
Randomized singular value decomposition
The randomized singular value decomposition (randomized SVD, or RSVD) is a numerical linear algebra algorithm that computes an approximate truncated SVD of a large matrix using random sampling.
Randomness
Randomness is the absence of exact predictability in the outcome of a process, modeled by assigning probabilities to each possible outcome and quantified by entropy.
Randomness test
A randomness test is a statistical procedure judging whether an ordered data sequence was produced randomly, detecting trends, oscillation, and autocorrelation; common examples include the Wald–Wolfowitz runs test.
Randy Ewoldt
Randy H. Ewoldt is an American rheologist and Alexander Rankin Professor at the University of Illinois Urbana-Champaign, known for measures of nonlinear viscoelasticity and a 2014 PECASE award.
Ranelic acid
Ranelic acid (C12H10N2O8S) is a thiophene tetracarboxylic acid whose divalent strontium salt, strontium ranelate (Protelos, Osseor), treated postmenopausal osteoporosis in the EU before 2020 withdrawal over cardiovascular risks.
Raney nickel
Raney nickel is a porous, hydrogen-loaded nickel catalyst made by leaching aluminum from a nickel-aluminum alloy, developed by Murray Raney in 1926 and widely used in hydrogenation.
Ranga Myneni
Ranga B. Myneni is a remote-sensing scientist who studies vegetation from satellites and has been a professor at Boston University since 1997, known for satellite evidence of high-latitude greening.
Rangaswamy Srinivasan
Rangaswamy Srinivasan, born 1929 in Madras, India, is a physical chemist who discovered ablative photodecomposition at IBM, the far-ultraviolet laser etching underlying LASIK and PRK eye surgery.
Range (statistics)
The range in statistics is a measure of dispersion, the difference between the largest and smallest values in a data set, used mainly in quality control charts.
Range of a projectile
The range of a projectile is the horizontal distance it travels from launch to impact, maximized at a launch angle of 45° when air resistance is neglected.
Rangeland
Rangeland is land with natural grasses, shrubs, or scattered trees suitable for grazing, managed through ecological processes rather than cultivation, and covering over half of Earth's land.
Rangifer
Rangifer, also called Tarandus, was a small, now-obsolete northern constellation representing a reindeer, created by Pierre Charles Le Monnier to commemorate Maupertuis's expedition to Lapland.
Rank (linear algebra)
The rank of a matrix is the dimension of the space spanned by its columns, equivalently its rows, equal to the number of pivots after row reduction.
Rank correlation
Rank correlation is a family of statistics that measures association between two variables by comparing ranks, with Spearman's ρ and Kendall's τ as the standard coefficients.
Rank of a partition
The rank of a partition is a statistic introduced by Freeman Dyson in 1944, defined as the largest part minus the number of parts, explaining Ramanujan's congruences.
Rank reduction (statistics)
Rank reduction is a statistical technique that approximates a data or parameter matrix by one of lower rank, minimizing squared error; in multivariate regression it appears as reduced-rank regression, introduced by T. W. Anderson in 1951.
Rank regression
Rank regression is a nonparametric regression method that fits models to the ranks of the data instead of raw values, reducing sensitivity to outliers and distributional assumptions.
Rank-into-rank cardinal
A rank-into-rank cardinal is the critical point of a nontrivial elementary embedding from some rank into itself, a hypothesis at the top of the large cardinal hierarchy in set theory.