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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.

© 2026 ScholarGate · A research-method reference library
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72 methods in Social Sciences · StatisticsClear
Methods at the intersection of your two filters.
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demography

Age-Period-Cohort Model

The age-period-cohort (APC) model decomposes variation in a vital rate — mortality, incidence, fertility — into three temporal dimensions: the age of individuals, the calendar period of observation, and the birth cohort to which they belong. It is the standard framework for asking whether a trend reflects how risk chan

2 sources1983
archaeology

Amino Acid Racemization

Amino acid racemization (AAR) dating estimates the age of biogenic materials such as mollusc shell, ostrich eggshell, bone, and teeth from the slow chemical conversion of amino acids from one mirror-image form to the other after an organism dies. Living tissue builds proteins almost entirely from left-handed (L) amino

2 sources1997
archaeology

Argon-Argon Dating

Argon-argon (40Ar/39Ar) dating is the modern, high-precision successor to conventional potassium-argon dating, in which the parent potassium is measured indirectly by converting it to a measurable argon isotope inside a nuclear reactor. A potassium-bearing sample is irradiated so that potassium-39 transmutes into argon

1 source1999
demography

Arriaga Decomposition

Arriaga decomposition is a demographic technique that breaks down the difference in life expectancy between two life tables — two countries, two time points, or two groups — into the contributions of mortality change at each age. Introduced by Eduardo Arriaga in 1984, it tells the analyst not just that life expectancy

2 sources1984
archaeology

Bayesian Chronological Modeling

Bayesian chronological modeling refines archaeological chronologies by combining the calibrated probability distributions of individual radiocarbon dates with prior archaeological knowledge — most importantly the stratigraphic order of samples and their grouping into phases — within a single Bayesian model. Rather than

2 sources2009
demography

Bongaarts Proximate Determinants

The Bongaarts framework of the proximate determinants of fertility decomposes a population's fertility into a biological maximum reduced by a small set of directly fertility-inhibiting factors: the proportion of women in sexual unions, contraceptive use, induced abortion, and postpartum infecundability. By expressing o

2 sources1978
demography

Brass Growth Balance Method

The Brass growth balance method estimates how complete a country's death registration is when vital statistics are incomplete but a census age distribution exists. Developed by William Brass in 1975, it rests on a simple demographic accounting identity applied above every age: in a stable population the rate at which p

1 source1975
demography

Brass P/F Ratio Method

The Brass P/F ratio method is the foundational technique of indirect fertility estimation, designed to correct fertility levels in populations whose vital registration is incomplete but where a census or survey reports both recent births and lifetime children ever born. It compares F — the period fertility a synthetic

2 sources1964
demography

Brass Relational Logit Model

The Brass relational logit model is a two-parameter system for representing and smoothing a life table by relating it to a chosen standard. Introduced by William Brass in 1971, it transforms the survivorship function with a logit and posits that the logits of any two life tables are linearly related, so that an entire

2 sources1971
demography

Child-Woman Ratio

The child-woman ratio is the number of young children, usually those under five, per woman of reproductive age in a population. Computed from a single census age-sex distribution, it is the simplest indirect indicator of fertility, designed for settings where birth registration is absent or unreliable. Because young ch

1 source1900
demography

Coale Fertility Indices

Coale's fertility indices are a set of standardized measures — If (overall fertility), Ig (marital fertility), Ih (nonmarital fertility), and Im (proportion married, an index of marriage) — that express a population's childbearing relative to the highest reliably recorded natural-fertility schedule, that of the Hutteri

2 sources1969
demography

Coale-Demeny Model Life Tables

The Coale-Demeny regional model life tables are a system of standard age patterns of mortality, distilled from hundreds of empirical life tables into four regional families — North, South, East, and West — each indexed by a mortality level. Given only a single summary of mortality, such as life expectancy at birth or a

2 sources1966
demography

Coale-McNeil Marriage Model

The Coale-McNeil model is a parametric description of how first marriages are distributed by age. Ansley Coale and Donald McNeil showed in 1972 that the age pattern of first marriage in widely different populations has a common shape, captured by a single standard curve that can be shifted and stretched. Three paramete

2 sources1972
demography

Coale-Trussell Model

The Coale-Trussell model is a two-parameter parametric description of the age pattern of marital fertility, introduced by Ansley Coale and James Trussell in 1974. It expresses observed age-specific marital fertility as a standard natural-fertility schedule scaled by an overall level parameter M and modulated by an age-

2 sources1974
demography

Cohort-Component Projection

Cohort-Component Projection is the standard demographic method for forecasting future population size and age-sex structure by explicitly tracking births, deaths, and migration for each age-sex cohort across discrete time steps. Systematically formalized in the textbook literature by Preston, Heuveline, and Guillot (20

1 source2001
archaeology

Contextual Seriation

Contextual seriation, also called occurrence or sequence seriation, is a relative-dating method that orders discrete archaeological units — typically graves or closed deposits — using only the presence or absence of artifact types within them. Its logic is the lifespan assumption: each type is introduced, used continuo

2 sources1899
archaeology

Cortex Ratio Analysis

Cortex ratio analysis is a quantitative method for assessing whether a lithic assemblage represents the complete reduction of the stone present, or whether pieces have been carried into or out of the deposit. Its insight is that every stone nodule begins entirely covered by a weathered outer rind, or cortex, and that k

2 sources2008
demography

Das Gupta Decomposition

Das Gupta decomposition is the general framework for standardizing and decomposing a difference between summary rates when several factors act at once and more than two populations must be compared. Developed by Prithwis Das Gupta and codified in his 1993 U.S. Census Bureau manual, it generalizes Kitagawa's two-populat

2 sources1993
demography

Demographic Balancing Equation

The demographic balancing equation is the fundamental accounting identity of population change: a population at the end of a period equals its size at the start, plus births, minus deaths, plus in-migrants, minus out-migrants. It is the bookkeeping rule that ties together all the components of population dynamics and g

2 sources1976
demography

Dependency Ratio

The age dependency ratio is a simple summary measure of a population's age structure that expresses the number of people in 'dependent' age groups — children and the elderly — relative to those of working age, conventionally per 100 working-age persons. It is split into a youth dependency ratio and an old-age dependenc

1 source1956
demography

Direct Standardization

Direct standardization is a demographic technique that makes summary rates comparable across populations by applying each population's group-specific rates — most often age-specific death or disease rates — to a single, common standard population structure. The resulting directly standardized rate answers a counterfact

2 sources2001
archaeology

Frequency Seriation

Frequency seriation is a relative-dating technique that orders archaeological assemblages in time by the changing proportions of the artifact types they contain. Its premise is that any cultural type is introduced, gradually becomes popular, peaks, and then declines, so that the relative frequency of a type traces a si

2 sources1962
demography

Gompertz-Makeham Law of Mortality

The Gompertz-Makeham law is the foundational parametric model of adult human mortality. Benjamin Gompertz showed in 1825 that the force of mortality rises exponentially with age, and William Makeham added an age-independent background term in 1860 to account for deaths from causes unrelated to ageing. The combined law

2 sources1860
demography

Gross Reproduction Rate

The gross reproduction rate is the average number of daughters a woman would bear over her lifetime if she experienced a given set of age-specific fertility rates and survived through all her childbearing years. It is a single-sex reproduction measure: by counting only daughters, it tracks how a generation of women rep

1 source1928
demography

Healthy Life Expectancy

Healthy life expectancy partitions ordinary life expectancy into the years a person can expect to live in good health and the years expected to be lived with disability or ill health. Building on the life table, the classic Sullivan method weights each age interval's person-years by the prevalence of good health, so th

2 sources1971
demography

Heligman-Pollard Model

The Heligman-Pollard model is an eight-parameter parametric law that describes the age pattern of mortality across the entire human lifespan in a single equation. Introduced by Larry Heligman and John Pollard in 1980, it represents the odds of dying at each age as the sum of three additive components — a rapidly declin

1 source1980
demography

Indirect Standardization

Indirect standardization is a demographic technique for comparing summary rates when a study population's own group-specific rates are too sparse to be reliable. Instead of reweighting the study population's rates, it applies a trusted standard schedule of group-specific rates to the study population's own structure to

1 source2001
archaeology

Intrasite Spatial Analysis

Intrasite spatial analysis studies how artifacts and features are distributed within a single site or living floor in order to reconstruct how space was used. Where settlement-pattern analysis treats whole sites as points, intrasite analysis zooms in to the scatter of tools, debris, hearths, and structures across an ex

2 sources1976
demography

Keyfitz Entropy

Keyfitz's entropy, usually written H, is a dimensionless summary of a life table that measures how sensitive life expectancy is to a proportional change in mortality, and equivalently how unequal the distribution of ages at death is. Introduced by Nathan Keyfitz, it is the elasticity of life expectancy at birth with re

2 sources1977
demography

Kitagawa Decomposition

Kitagawa decomposition is a demographic technique that splits the difference between two summary rates — such as two crude death rates, birth rates, or prevalence figures — into the part attributable to differences in the underlying group-specific rates and the part attributable to differences in population composition

2 sources1955
archaeology

Lead Isotope Provenance

Lead isotope provenance traces metals — copper, silver, lead, and lead-bearing glazes and pigments — back to the ore deposits from which they were extracted, by measuring the ratios of lead's four naturally occurring isotopes. Three of those isotopes (lead-206, -207, -208) are produced by the slow radioactive decay of

2 sources2016
demography

Lee-Carter Model

The Lee-Carter model is a stochastic framework for modeling and forecasting age-specific mortality rates, introduced by Ronald Lee and Lawrence Carter in their landmark 1992 paper. It decomposes the logarithm of age-specific death rates into an age pattern of mortality, a time-varying index of mortality level, and an a

1 source1992
demography

Lee-Carter Mortality Model

The Lee-Carter model is the benchmark method for forecasting human mortality. Introduced by Ronald Lee and Lawrence Carter in 1992 for U.S. data, it captures the entire schedule of age-specific death rates with a remarkably parsimonious structure: the logarithm of the death rate at each age is a fixed average age profi

2 sources1992
demography

Lexis Diagram

The Lexis diagram is a geometric bookkeeping device that places every demographic event in a two-dimensional grid of age against calendar time, so that each person's life traces a diagonal line and each cohort fans out as a band of parallel lifelines. Named after the German statistician Wilhelm Lexis, it is the foundat

1 source1875
demography

Life Table

A life table is a systematic, age-structured summary of the mortality experience of a population. It traces a hypothetical cohort of births — conventionally 100,000 — through successive age intervals, recording how many survive, how many die, and how many person-years are lived at each interval. The method was formaliz

1 source1984
demography

Lifespan Inequality

Lifespan inequality measures how unequally length of life is distributed within a population — the spread of the life-table ages at death, not just their average. Two populations can share the same life expectancy yet differ sharply in how predictable death is: in one nearly everyone reaches old age, in the other death

2 sources2003
demography

Mean Age at Childbearing

The mean age at childbearing is the average age of mothers at the birth of their children, computed as the fertility-rate-weighted mean of maternal age over the age-specific fertility schedule. As the first moment of the fertility curve, it summarizes the tempo — the timing — of childbearing in a single number, complem

1 source1968
linguistics

Measure of Textual Lexical Diversity (MTLD)

The Measure of Textual Lexical Diversity (MTLD) is a length-robust index of vocabulary richness introduced by Philip McCarthy in 2005 and validated by McCarthy and Jarvis in 2010. Rather than computing a single ratio over the whole text, MTLD reads the text word by word, tracking a running type-token ratio, and counts

2 sources2005
demography

Migration Models

Migration models are quantitative frameworks for explaining and forecasting population movement between geographic units. Lee's (1966) push-pull theory classifies factors at origin and destination into positive and negative forces, modulated by intervening obstacles. Widely used by demographers, regional planners, and

1 source1966
archaeology

Minimum Number of Individuals (MNI)

The minimum number of individuals, abbreviated MNI, estimates the smallest number of whole animals that could account for the bones identified in a faunal assemblage. Where NISP counts identifiable pieces, MNI translates those pieces into a defensible lower bound on the number of animals by exploiting the fact that eac

2 sources2008
demography

Multiregional Demography

Multiregional demography extends the classical tools of mathematical demography — the life table, the Leslie matrix, and stable-population theory — from a single closed population to a system of interconnected regions linked by migration. Developed by Andrei Rogers, it tracks people not only by age but by region of res

2 sources1975
demography

Multistate Life Table

The multistate life table, also called the increment-decrement life table, generalizes the ordinary life table to populations that move among several living states — such as healthy and disabled, married and unmarried, or employed and unemployed — as well as the absorbing state of death. Using age-specific transition r

1 source1975
archaeology

NAA Provenance

NAA provenance is the use of instrumental neutron activation analysis (INAA) to determine where archaeological ceramics, obsidian, and other materials were made or obtained, by exploiting their high-precision multi-element chemical fingerprints. INAA irradiates a sample with neutrons, making its elements briefly radioa

1 source2003
demography

Net Migration Rate

The net migration rate expresses the net effect of migration on a population's size as a rate: net migration — in-migrants minus out-migrants over a period — divided by the population at risk, conventionally stated per 1000 people. It is the migration counterpart to the rate of natural increase and a standard component

2 sources1976
demography

Net Reproduction Rate

The net reproduction rate (NRR) is the demographic measure of generational replacement: the average number of daughters a woman would bear who survive to the age their mother was when she bore them, given the period's age-specific fertility rates and female mortality. By combining fertility with survival, the NRR answe

1 source2001
archaeology

Number of Identified Specimens (NISP)

The number of identified specimens, universally abbreviated NISP, is the most basic quantitative measure in zooarchaeology: a simple count of every bone or bone fragment that an analyst can identify to a taxon. It is the first number computed for almost any faunal assemblage because it is fast, transparent, additive ac

2 sources2008
archaeology

Osteological Age & Sex Estimation

Osteological age and sex estimation is the foundational bioarchaeological procedure for building a biological profile from human skeletal remains: estimating how old an individual was at death and determining their biological sex. The skeleton changes in patterned ways across life — teeth form and erupt, growth plates

1 source1994
demography

Own-Children Method

The own-children method is an indirect technique for estimating age-specific fertility rates for the years preceding a census or survey, using only a single cross-sectional dataset in which children can be linked to their mothers within the same household. By reverse-surviving matched mother-child pairs back through ti

1 source1986
archaeology

Paleodemographic Analysis

Paleodemographic analysis reconstructs the demographic life of past populations — their mortality schedules, life expectancy, age structure, and fertility — from the age-at-death distributions of skeletal samples. It begins from the per-individual ages produced by osteological estimation and aggregates them into life t

2 sources1982
demography

Parity Progression Ratio

A parity progression ratio is the conditional probability that a woman who has already had a given number of children goes on to have one more. By converting a static parity distribution into a sequence of birth-by-birth transition probabilities, the method reveals where childbearing stops within a cohort and lets demo

1 source1953
archaeology

Point Pattern Settlement Analysis

Point pattern settlement analysis treats archaeological sites as points in space and uses spatial statistics to test whether their distribution is clustered, dispersed, or random. The motivating question is interpretive: clustering may signal social aggregation, defense, or attraction to localized resources, while regu

2 sources1976
demography

Pollard Decomposition

Pollard's decomposition breaks a difference in life expectancy between two populations into additive contributions from each age, showing exactly how much of the gap is due to mortality differences at infancy, in midlife, or in old age. John Pollard derived a continuous-age formula expressing the life-expectancy differ

2 sources1982
demography

Population Momentum

Population momentum is the tendency of a growing population to keep growing for decades even after fertility falls to the replacement level, simply because its age structure is heavily weighted toward young people who have yet to reach childbearing age. Introduced by Nathan Keyfitz in 1971, the momentum factor measures

2 sources1971
demography

Population Pyramid Analysis

Population pyramid analysis is the description and interpretation of a population's age-sex structure through a back-to-back horizontal bar chart, with males on one side, females on the other, and age groups stacked from youngest at the bottom to oldest at the top. The shape of the pyramid encodes a population's fertil

1 source1874
archaeology

Potassium-Argon Dating

Potassium-argon (K-Ar) dating is a radiometric technique that determines the age of volcanic rocks and minerals from the slow radioactive decay of potassium-40 to argon-40. Potassium is abundant in many rock-forming minerals, and a fixed fraction of its naturally radioactive isotope decays to argon gas at a precisely k

2 sources1999
demography

Preston-Coale Method

The Preston-Coale method, also called the synthetic extinct generations method, estimates the completeness of death registration by rebuilding a population from the very deaths it records. Introduced by Samuel Preston and Ansley Coale in 1982, it uses the variable-r relations of a non-stable population to project each

2 sources1982
archaeology

Radiocarbon Calibration

Radiocarbon calibration converts a laboratory radiocarbon measurement into a probability distribution over actual calendar years. It is necessary because the assumptions behind a raw radiocarbon age are not exactly true: the concentration of carbon-14 in the atmosphere has varied over time, so a measured radiocarbon ag

2 sources2020
demography

Relational Gompertz Fertility Model

The relational Gompertz model expresses any population's cumulative fertility schedule as a simple linear transformation of a fixed standard schedule, after both are mapped through a double-logarithm (gompit) transform. Developed by William Brass and given its widely used standard by Heather Booth, it characterizes the

2 sources1984
demography

Siler Mortality Model

The Siler model is a parametric description of the entire age pattern of mortality, from birth to extreme old age, built as the sum of three competing hazards: a high but rapidly declining risk in early life, a roughly constant background risk through the prime adult years, and an exponentially rising risk of senescenc

2 sources1979
archaeology

Single-Aliquot Regenerative-Dose (SAR) Protocol

The single-aliquot regenerative-dose (SAR) protocol is the measurement methodology that underlies modern optically stimulated luminescence (OSL) dating, providing the recipe by which the equivalent dose of a sediment sample is estimated from a single sub-sample. Its central problem is that exposing a mineral grain to l

1 source2000