42,772 articles
Expected value of sample information
The expected value of sample information (EVSI) is a decision-theoretic measure of the average worth of a proposed study, the expected gain from updating a decision with its data.
Expectile regression
Expectile regression estimates conditional expectiles, asymmetric least-squares analogs of quantiles, using smooth squared loss that is computationally simpler than quantile regression and carries tail magnitude information.
Experience sampling method
The experience sampling method (ESM), also called experience sampling, is a research procedure in which participants repeatedly report thoughts, feelings, and context in daily life, typically via mobile device.
Experiment
An experiment is a study in which the investigator assigns subjects to treatment and control groups, at random, to produce data that settles questions of cause or effect.
Experimental Lakes Area
The Experimental Lakes Area is a research region of 58 small lakes in northwestern Ontario, Canada, set aside in 1968, where scientists manipulate entire lake ecosystems to study pollution.
Experimental physics
Experimental physics is the branch of physics that tests theories, reveals new phenomena, and provides evidence for entities like the electron through measurement and apparatus.
Experimental Storage Ring
The Experimental Storage Ring (ESR) is a heavy-ion storage and cooler ring at the GSI facility in Darmstadt, Germany, storing and cooling highly charged stable and radioactive ions.
Experimental studies of decoherence
Experimental studies of decoherence are laboratory measurements of how quantum superpositions lose coherence to their environment, first controlled in 1996 at the École Normale Supérieure in Paris.
Experiments on Plant Hybridization
Experiments on Plant Hybridization (Versuche über Pflanzen-Hybriden) is an 1866 paper by Gregor Mendel reporting eight years of pea crossing experiments that established the founding laws of genetics.
Experimentum crucis
Experimentum crucis, or crucial experiment, is a decisive experiment meant to choose between two competing theories, most famously Isaac Newton's 1672 two-prism experiment showing white light mixes colored rays.
Expert elicitation
Expert elicitation is a structured method for synthesizing expert judgments into probability distributions when data are sparse or absent, used in health care, natural hazards, and forecasting.
Expertise in policy (science advice)
Expertise in policy, or science advice, brings scientific and technical knowledge into government decisions without becoming advocacy, organized around Roger Pielke Jr.'s 2007 framework of four expert roles.
Explanatory sequential mixed methods design
The explanatory sequential mixed methods design is a two-phase research design in which quantitative data are collected first and qualitative data are collected second to explain the quantitative results.
Explanatory trial
An explanatory trial is a randomized controlled trial testing whether an intervention works under ideal, tightly controlled conditions, a concept introduced by Schwartz and Lellouch in 1967.
Explicit and implicit methods
Explicit and implicit methods are the two families of time-stepping schemes for numerically integrating ODEs and PDEs: explicit steps are cheap but step-size limited, implicit steps cost more but stay stable.
Explicit formulae (L-function)
An explicit formula for an L-function is an identity in analytic number theory expressing a sum over the L-function's nontrivial zeros as a sum over prime powers.
Explicit time integration
Explicit time integration is a class of numerical methods that advance time-dependent differential equations step by step using only known values, favored for crash and shock simulation.
Explicitly correlated F12 methods
Explicitly correlated F12 methods are quantum-chemistry methods that add terms depending explicitly on interelectronic distance r12, so triple-zeta basis sets reach near complete-basis-set accuracy at small extra cost.
Exploratory causal analysis
Exploratory causal analysis, also known as causal discovery or data causality, uses observational data to learn the causal structure of a system of variables, typically as a causal graph.
Exploratory data analysis
Exploratory data analysis, also called explorative data analysis, is a statistical approach that examines data first with descriptive statistics and graphs before hypothesis testing, named by John Tukey in 1977.
Exploratory factor analysis
Exploratory factor analysis (EFA) is a multivariate statistical method that models correlations among observed variables as the shared influence of a smaller number of unobserved common factors, without imposing a factor structure in advance.
Exploratory graph analysis
Exploratory graph analysis (EGA) is a network psychometrics method that estimates the number of dimensions in data via community detection on a regularized correlation network.
Exploratory research
Exploratory research is a mode of scientific inquiry used when a problem is loosely defined or little studied, generating concepts and hypotheses rather than testing them.
Exploratory sequential mixed methods design
The exploratory sequential mixed methods design is a research design that runs a qualitative phase first, then a quantitative phase to test or generalize the findings.
Exploratory structural equation modeling
Exploratory structural equation modeling (ESEM) is a statistical framework, introduced by Tihomir Asparouhov and Bengt Muthén in 2009, that combines exploratory factor analysis with the confirmatory machinery of structural equation modeling.
Explosive cyclogenesis
Explosive cyclogenesis, sometimes called bombogenesis, is the rapid deepening of an extratropical cyclone; the resulting storm is colloquially called a bomb cyclone, with hurricane-force winds.
Exponential decay
Exponential decay is the process in which a quantity decreases at a rate proportional to its current value, so it falls as an exponential function of time.
Exponential distribution
The exponential distribution, also called the negative exponential distribution, is a continuous probability distribution describing waiting times between independent events occurring at a constant average rate.
Exponential family
The exponential family is a class of probability distributions sharing one exponential density form, including the Gaussian, binomial, Poisson, and gamma, and underlying generalized linear models.
Exponential formula
The exponential formula, also called the polymer expansion, is a theorem of enumerative combinatorics stating that the EGF of all labeled structures equals the exponential of the EGF of connected ones.