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One catalogue of research methods — learn how each one works, when to use it, and what it can’t do.

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Entries are compiled from published sources for reference. Verifying the accuracy and suitability of any information for your own use remains your responsibility.

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MethodStatistics1,836AI & ML1,661Decision Sciences932Research Methods1,354Measurement1,745Causal & Evidence532Research Practice118
44 methods in Natural Sciences · MeasurementClear
Methods at the intersection of your two filters.
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optics

ABCD Matrix

The ABCD matrix, or ray transfer matrix method, is a compact algebraic framework for analyzing optical systems. Introduced by Kogelnik and Li in 1966, it represents the linear transformation of ray position and angle (or Gaussian beam parameters) through optical elements. This method is foundational in laser physics, G

3 sources1966
acoustics

Acoustic Holography

Near-Field Acoustic Holography (NAH) is a technique for reconstructing 3D acoustic sound fields and visualizing sound radiation from sources by measuring pressure at a dense microphone array in the near field. Pioneered by Maynard, Williams, and Lee in 1985, NAH extends holographic principles from optics to acoustics,

3 sources1985
geophysics

Ambient Noise Tomography

Ambient Noise Tomography (ANT) is a seismic imaging method that extracts surface wave information from long-term records of seismic background noise, enabling high-resolution imaging of crustal and upper mantle structure. Developed by Shapiro, Campillo, and colleagues in 2005, ANT has revolutionized seismic imaging by

2 sources2005
analytical chemistry

Analytical Method Validation

Analytical method validation is a systematic process of establishing documented evidence that an analytical method is suitable for its intended use in measuring the identity, purity, strength, and/or content of a substance. Governed by regulatory agencies (FDA, ICH) and industry standards (USP, EP), validation ensures

3 sources1995
analytical chemistry

Atomic Absorption Spectroscopy

Atomic absorption spectroscopy is an analytical technique that measures the concentration of metal elements by detecting the absorption of light by ground-state metal atoms in the gaseous state. Invented by Alan Walsh in 1955, it rapidly became the standard method for trace metal analysis in environmental, clinical, ag

3 sources1955
optics

Beam Propagation Method

The Beam Propagation Method is a computational technique for simulating the propagation of optical beams through slowly varying, weakly guiding structures. Developed by Feit and Fleck in 1978, BPM exploits the paraxial approximation to reduce the full vector wave equation to a scalar or vector envelope equation, enabli

3 sources1978
particle physics

Cherenkov Detection

Cherenkov detection exploits the emission of electromagnetic radiation when a charged particle travels through a medium faster than light travels in that same medium. This enables precise particle identification and mass measurement through analysis of Cherenkov light patterns, forming a cornerstone technology in moder

3 sources1934
chemistry

Column Chromatography

Column chromatography is a liquid separation technique in which a stationary phase (typically silica gel or alumina) is packed into a vertical column, and a mobile phase (solvent) percolates through it to separate mixture components. Pioneered by Mikhail Tsvet in 1903, column chromatography remains the workhorse of org

2 sources1903
chemistry

Coordination Compound Synthesis

Coordination compound synthesis is the methodology for preparing metal-ligand complexes, ranging from simple aqueous solutions of metal ions to sophisticated organometallic catalysts and biological metalloproteins. Developed systematically from the 1960s onward by pioneers like Geoffrey Wilkinson and others, coordinati

2 sources1960
analytical chemistry

Coulometry

Coulometry is an electrochemical analytical method that determines the concentration of an analyte by measuring the total electric charge (in coulombs) required to oxidize or reduce the analyte completely at an electrode. Developed by James J. Lingane in the 1940s, coulometry is highly accurate because it is based on f

3 sources1945
chemistry

Crystal Field Theory

Crystal Field Theory (CFT) is a model that explains the electronic structure, color, magnetism, and reactivity of coordination complexes by considering how the electric field created by surrounding ligands perturbs the d-orbitals of a central metal ion. Developed by Hans Bethe in 1929 and refined throughout the 20th ce

2 sources1929
geophysics

Electrical Resistivity Tomography

Electrical Resistivity Tomography (ERT) is an active-source geophysical method that maps the spatial distribution of electrical resistivity in the subsurface by injecting current between two electrodes and measuring potential differences across an array of receiver electrodes. Advanced as a practical technique by Loke

2 sources1996
optics

Finite-Difference Time-Domain

The Finite-Difference Time-Domain method is a computational technique for solving Maxwell's equations by discretizing space and time on a grid. Introduced by Kane Yee in 1966, FDTD is a foundational approach in computational electrodynamics and optical simulation, enabling direct modeling of electromagnetic wave propag

3 sources1966
analytical chemistry

Flow Injection Analysis

Flow injection analysis is an automated continuous-flow technique that rapidly injects a sample plug into a flowing stream of carrier solution, where it mixes with reagents and is detected online before reaching the detector. Developed by Jaromir Ruzicka and Elo Hansen in 1975, FIA revolutionized analytical chemistry b

3 sources1975
chemistry

Functional Group Identification

Functional group identification is the systematic determination of chemical functional groups present in organic molecules using spectroscopic, chemical, and structural data. Developed throughout the 20th century alongside spectroscopy and analytical chemistry, this methodology enables rapid structure elucidation by fo

2 sources
geophysics

Ground-Penetrating Radar

Ground-Penetrating Radar (GPR) is a near-surface geophysical method that uses high-frequency electromagnetic pulses (typically 10 MHz to 2.5 GHz) to image shallow subsurface structures with exceptional spatial resolution. Pioneered by Davis and Annan in 1989, GPR is widely used in archaeology, civil engineering, enviro

2 sources1989
analytical chemistry

Inductively Coupled Plasma Spectrometry

Inductively coupled plasma spectrometry is a powerful multi-element analytical technique that ionizes a sample in a high-temperature plasma and measures the emitted light (ICP-OES) or ion masses (ICP-MS) to determine elemental concentrations. Developed in the 1960s by Stanley Greenfield, ICP techniques have become the

3 sources1964
chemistry

Infrared Spectroscopy Identification

Infrared (IR) spectroscopy measures the absorption of infrared radiation by chemical bonds, creating a spectrum unique to each compound. Discovered by William Herschel in 1800 and developed into a practical analytical tool in the mid-20th century, IR spectroscopy is indispensable for rapidly identifying functional grou

2 sources1800
optics

Interferogram Fringe Analysis

Interferogram fringe analysis is a computational methodology for extracting quantitative information from interference fringe patterns recorded in optical systems. Rooted in Thomas Young's 1801 double-slit experiment and formalized in 20th-century metrology, this approach interprets the spatial patterns of constructive

3 sources1801
analytical chemistry

Ion Chromatography

Ion chromatography is a liquid chromatography method that separates ions and polar molecules based on their relative affinity for the ion exchange resin in the column. Developed by Hamish Small in 1975, it combines ion-exchange separation with conductivity detection, enabling rapid, sensitive, and simultaneous determin

3 sources1975
geophysics

Isotope Ratio Mass Spectrometry

Isotope Ratio Mass Spectrometry (IRMS) is an analytical technique that measures the relative abundance of stable isotopes (H, C, N, O, S) and some radiogenic isotopes (e.g., ⁸⁷Sr/⁸⁶Sr) in samples with high precision. Standardized by Coplen and colleagues, IRMS enables paleoclimate reconstruction, source tracing (diet,

2 sources1994
optics

Jones Calculus

Jones calculus is a mathematical formalism for analyzing the propagation and manipulation of polarized light using vectors and matrices. Developed by Robert Clark Jones in 1941, it represents the electric field of a coherent optical beam as a two-component complex vector (Jones vector) and optical elements as matrices

3 sources1941
chemistry

Ligand Field Analysis

Ligand Field Theory (LFT) is an advanced model of metal-ligand bonding that combines crystal field theory with molecular orbital theory. Developed systematically by Brian Norman Figgis and others from the 1960s onward, LFT provides quantitative predictions of electronic structure, magnetism, spectra, and reactivity of

2 sources1960
chemistry

Molecular Symmetry Analysis

Molecular symmetry analysis is the systematic application of group theory to understand the structure, bonding, spectroscopy, and reactivity of molecules. Developed comprehensively by F. Albert Cotton and others from the 1960s onward, this framework uses the mathematical properties of molecular symmetry to predict allo

2 sources1960
optics

Mueller-Stokes Calculus

Mueller-Stokes calculus is a mathematical framework for describing and analyzing the polarization properties of light, including partially polarized and unpolarized light. Grounded in George Gabriel Stokes' 1852 work on polarization parameters and extended by Hans Mueller in 1948, this formalism uses the four-component

3 sources1852
chemistry

Nucleophilic Substitution Analysis

Nucleophilic substitution reaction analysis is the systematic study of how nucleophiles attack electrophilic carbons (or other atoms), displacing leaving groups and forming new bonds. Formalized by Hughes, Ingold, and Winstein from the 1930s onward, this framework distinguishes mechanistic pathways (SN1 vs. SN2) and en

2 sources1937
geoscience

Petrographic Analysis

Petrographic analysis is the microscopic examination of rock thin sections to determine mineral composition, grain size, texture, and diagenetic alteration. Pioneered by Sorby in 1858, this method remains the gold standard for understanding lithology and has evolved to include quantitative image analysis and cathodolum

3 sources1858
optics

Plasmonic Resonance

Plasmonic resonance refers to the collective oscillation of free electrons in metallic nanostructures that interact strongly with light, resulting in dramatic enhancements of electric fields, absorption, and scattering. First discovered by Kretschmann and Raether in 1968, plasmonic resonance is now central to nanophoto

3 sources1968
analytical chemistry

Potentiometric Titration

Potentiometric titration is an electrochemical method of analysis that measures the potential difference between a reference electrode and an indicator electrode as a titrant is gradually added to a solution. Developed in the early 20th century, it allows precise determination of the concentration of analytes without r

3 sources1909
optics

RCWA

Rigorous Coupled-Wave Analysis is a semi-analytical computational method for solving Maxwell's equations in periodic structures such as diffraction gratings and photonic crystals. Developed by Moharam and Gaylord in 1981, RCWA expands the electromagnetic fields in each periodic region into Fourier series and couples th

3 sources1981
geophysics

Receiver Function Analysis

Receiver Function (RF) analysis is a seismic method that isolates P-to-S wave conversions at crustal and mantle discontinuities using teleseismic records from distant earthquakes. Introduced by Langston in 1979, RF analysis provides a cost-effective way to determine crustal thickness, Poisson's ratio, and upper mantle

2 sources1979
chemistry

Recrystallization

Recrystallization is a classical purification technique in which a solid compound is dissolved in hot solvent, then allowed to crystallize upon cooling, yielding pure crystals while impurities remain in solution. Practiced for centuries in chemistry laboratories, recrystallization remains one of the most effective and

2 sources
chemistry

Redox Reaction Mechanism Analysis

Redox reaction mechanism analysis is the systematic study of electron transfer pathways in oxidation-reduction reactions. Formalized by Rudolph Marcus in the 1950s (earning him the Nobel Prize in 1992), this framework explains how electrons move between reactants, what factors control reaction rates, and how electronic

2 sources1956
geoscience

Seismic Reflection Interpretation

Seismic reflection interpretation is the process of extracting meaningful geological information from seismic survey data, which is collected by recording elastic waves reflected from rock layers beneath the surface. Developed and systematized in the mid-20th century, this method is foundational in petroleum exploratio

3 sources1960
analytical chemistry

Standard Addition Method

The standard addition method is a quantitative analytical technique that determines the concentration of an unknown analyte by measuring the response before and after adding a known quantity of the analyte (a standard) to the sample itself. This approach compensates for matrix effects and interference from other sample

3 sources1920
chemistry

Stereochemistry Analysis

Stereochemistry analysis is the systematic study of three-dimensional molecular structures, with emphasis on determining the spatial arrangement of atoms around chiral centers and assigning unambiguous names to stereoisomers. Formalized by Cahn, Ingold, and Prelog in 1966, the CIP (Cahn-Ingold-Prelog) rules provide an

2 sources1966
chemistry

Substitution Reaction Kinetics

Substitution reaction kinetics analysis is the systematic study of how fast nucleophiles replace leaving groups in organic and inorganic compounds. Formalized by Edward Hughes and Christopher Ingold in the 1930s, this framework distinguishes between bimolecular (SN2) and unimolecular (SN1) mechanisms, connecting mechan

2 sources1937
chemistry

Synthesis Route Planning

Synthesis route planning, grounded in retrosynthetic analysis, is a strategic approach to designing efficient chemical syntheses. Formalized by Elias James Corey in the 1960s (earning him the Nobel Prize in 1990), this methodology systematically deconstructs target molecules into simpler precursors and starting materia

2 sources1969
chemistry

Thin-Layer Chromatography

Thin-Layer Chromatography (TLC) is a planar chromatographic technique that separates compounds based on their differential affinities for a mobile and stationary phase. Developed by Egon Stahl in 1956, TLC remains one of the most accessible and widely used analytical methods in organic and inorganic chemistry, laborato

2 sources1956
analytical chemistry

UV-Vis Spectrophotometry

UV-Vis spectrophotometry is an optical analytical technique that measures the absorption of ultraviolet and visible light (wavelengths 190–900 nm) by substances in solution. Founded on the Beer-Lambert law (developed by August Beer and Pierre Bouguer), it is one of the oldest and most widely used quantitative analytica

3 sources1852
analytical chemistry

Voltammetry

Voltammetry is an electrochemical analytical technique that studies chemical reactions and properties of substances by measuring the current response as the potential applied to an electrode is systematically varied. Developed by Jaroslav Heyrovsky in the 1920s (polarography), modern voltammetry has become essential fo

3 sources1922
chemistry

X-Ray Crystallography

X-ray crystallography is a technique that determines the three-dimensional atomic structure of crystals by analyzing the diffraction patterns produced when X-rays pass through them. Developed by William Henry Bragg and William Lawrence Bragg in 1912, X-ray crystallography has become the gold standard for structure dete

2 sources1912
optics

Z-scan

The Z-scan technique is an experimental method for measuring nonlinear optical properties of materials, particularly third-order susceptibility and nonlinear absorption. Developed by Sheik-Bahae, Hagan, and Van Stryland in 1990, Z-scan uses a tightly focused laser beam and moves the sample along the beam propagation ax

3 sources1990
astronomy

Zeeman-Doppler Imaging

Zeeman-Doppler imaging is a technique for reconstructing stellar magnetic field maps by combining Doppler broadening of spectral lines with the Zeeman splitting caused by magnetic fields. Pioneered by Jean-Francois Donati in the 1990s, this method reveals how magnetic fields are distributed on stellar surfaces and how

3 sources1997