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Natural Sciences236

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MethodStatistics1,836 AI & ML1,661 Decision Sciences932 Research Methods1,354 Measurement1,745 Causal & Evidence532 Research Practice118

29 methods in Research Practice · StatisticsClear

Methods at the intersection of your two filters.

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Citation Distribution Modeling (Lognormal/Tsallis)

Citation distribution modeling studies the statistical shape of how citations are spread across papers and uses that shape to compare impact fairly across very different fields. The pivotal result, from Filippo Radicchi, Santo Fortunato, and Claudio Castellano in 2008, is that although raw citation distributions differ

Citation Half-Life and Literature Obsolescence

Citation half-life measures how quickly a body of literature ages by finding the median age of the documents being cited. Borrowing the metaphor of radioactive decay, Robert Burton and R. W. Kebler proposed in 1960 that scientific literatures grow obsolete at characteristic rates, and that the half-life, the time withi

Citing vs Cited Half-Life Asymmetry

A journal has two half-lives, and comparing them reveals its temporal personality. The cited half-life measures the median age of the articles the journal is cited for, capturing how long its own work stays useful. The citing half-life measures the median age of the references the journal's articles make, capturing how

research methodology

Cochrane RoB 2.0

RoB 2 is the Cochrane Collaboration's updated methodology for assessing the risk of bias in randomized controlled trials (RCTs). Published in 2019, it replaced the original Cochrane RoB tool with a more structured, transparent approach using signalling questions and domain-based judgments to evaluate five critical sour

Collaboration Distance and Erdős Number Analysis

Collaboration distance analysis measures how closely connected scientists are through chains of co-authorship. Two researchers who have written a paper together are at distance 1; if they share a co-author but never wrote together, distance 2; and so on. The most famous instance is the Erdős number, the collaboration d

Contemporary h-Index

The contemporary h-index, introduced by Sidiropoulos, Katsaros, and Manolopoulos in 2007, modifies Hirsch's h-index to reward recent scientific activity over old laurels. The plain h-index never decreases and treats a citation earned decades ago the same as one earned last year, so a researcher who has stopped publishi

Crown Indicator (CPP/FCSm)

The crown indicator, written CPP/FCSm, was the field-normalized citation impact measure developed at the Centre for Science and Technology Studies (CWTS) in Leiden and described by Moed, De Bruin, and Van Leeuwen in 1995. It compares a unit's observed citation rate with what would be expected given the fields, document

Disruption Index (CD-Index)

The disruption index, or CD index, classifies a scientific paper or patent by how the work that cites it treats the work it built on. Introduced by Russell Funk and Jason Owen-Smith in 2017 as a dynamic network measure of technological change, and popularized for science by Lingfei Wu, Dashun Wang, and James Evans in 2

e-Index (Excess Citations)

The e-index, proposed by Chun-Ting Zhang in 2009, isolates the citations that the h-index throws away. Inside the h-core of an author's h most-cited papers, the h-index implicitly credits each paper with only h citations and discards everything above that, even though top papers may have far more. The e-index recovers

Eigenfactor and Article Influence Score

The Eigenfactor Score and its per-article companion, the Article Influence Score, rank scholarly journals by treating the citation network as a system in which a citation from a prestigious journal counts for more than a citation from an obscure one. Carl Bergstrom introduced the Eigenfactor in 2007 using the same recu

Field-Normalized Citation Impact (MNCS)

The Mean Normalized Citation Score (MNCS) is the field-normalized citation impact indicator developed at the Centre for Science and Technology Studies (CWTS) in Leiden and articulated in Waltman and colleagues' 2011 paper on a new crown indicator. Raw citation counts cannot be compared across fields, because a molecula

g-Index (Egghe)

The g-index, introduced by Leo Egghe in 2006, is an author-level bibliometric indicator designed to repair a structural weakness of Hirsch's h-index: its insensitivity to the size of the most-cited papers. Where the h-index caps the credit any single paper can earn at h, the g-index lets exceptionally cited articles ra

Garfield's Law of Concentration

Garfield's Law of Concentration is the bibliometric principle that the bulk of the significant scientific literature is concentrated in a relatively small, largely multidisciplinary core of journals. Formulated by Eugene Garfield — founder of the Science Citation Index — and presented in his 1972 Science paper 'Citatio

hg-Index (Composite Hirsch-Egghe)

The hg-index, proposed by Alonso, Cabrerizo, Herrera-Viedma, and Herrera in 2010, fuses the two best-known author metrics into a single composite. The h-index is robust but ignores how heavily an author's top papers are cited, while Egghe's g-index rewards those highly cited papers but can be swayed by a single outlier

i10-Index

The i10-index is a deliberately simple author-level metric introduced by Google Scholar in 2011 for its Scholar Citations profiles. It counts the number of a researcher's publications that have each accumulated at least ten citations. Unlike the h-index, whose threshold depends on the rank of the paper, the i10-index a

Immediacy Index

The Immediacy Index measures how quickly a journal's articles are cited by counting the citations they receive in the very year they are published. Eugene Garfield, who created the Science Citation Index and the impact factor, introduced the immediacy index as part of the Institute for Scientific Information's journal-

Journal Self-Citation Analysis

Journal self-citation analysis separates the citations a journal gives to itself from the citations it gives to and receives from the wider literature, in order to understand a journal's internal coherence and to detect potential inflation of impact metrics. Ronald Rousseau showed in 1999 that a journal's citation curv

m-Quotient (Hirsch m)

The m-quotient, defined by Jorge Hirsch in the same 2005 paper that introduced the h-index, normalizes an author's h-index by the length of their scientific career. Because the h-index can only grow over time and never decreases, raw h-values systematically favor senior researchers and make it unfair to compare early-c

Mendeley Readership Analysis

Mendeley readership analysis uses the number of users who have saved an article to their personal library in the Mendeley reference manager as an indicator of scholarly attention. Ehsan Mohammadi and Mike Thelwall showed in 2014 that these reader counts have broad coverage, correlate moderately with later citations, an

Patent–Paper Citation Linkage (NPL)

Patent–paper citation linkage measures how strongly technology draws on science by analyzing the non-patent literature, or NPL, references that appear on patents. When a patent cites a scientific journal article rather than another patent, it leaves a traceable thread connecting an invention to the research it built on

Percentile-Based Citation Impact (PPtop10%)

Percentile-based citation impact replaces the average citation count with a paper's rank position within a properly defined reference set. Instead of asking how many citations a paper received, it asks where the paper falls in the citation distribution of comparable papers from the same field, year, and document type.

Price Index (Citation Recency)

The Price Index measures how strongly a field draws on recent literature by computing the percentage of its references that point to work published within the last few years. Derek de Solla Price, the founder of modern scientometrics, observed that the sciences differ sharply in how immediate their referencing is: hard

Relative Specialization / Activity Index

The Relative Specialization Index and the closely related Activity Index measure how much a country, institution, or other unit concentrates its research effort in a given field relative to a global benchmark. The Activity Index, popularized by J. Davidson Frame in the 1970s, compares a unit's share of its own output d

Scientific Collaboration Index (Co-Authorship Intensity)

The Scientific Collaboration Index family quantifies how collaborative a body of research is by analyzing the number of authors per paper. In his influential 1983 review of bibliometric studies of research collaboration, K. Subramanyam consolidated the main measures: the Degree of Collaboration (the proportion of multi

Sleeping Beauties and Delayed Recognition

A Sleeping Beauty is a publication that goes almost unnoticed for many years and then, sometimes decades later, suddenly attracts intense citation attention. Anthony van Raan introduced the metaphor to scientometrics in 2004, reporting the first systematic measurement of how often such delayed-recognition papers occur

Source Normalized Impact per Paper (SNIP)

The Source Normalized Impact per Paper, or SNIP, corrects a journal's citation rate for the citation behavior of its field so that journals in heavily cited and lightly cited disciplines can be compared on the same scale. Henk Moed introduced SNIP in 2010 with a distinctive twist: rather than classifying journals into

Technology Life Cycle Bibliometrics

Technology life cycle bibliometrics uses time series of patent and publication counts to locate where a technology sits in its developmental life cycle and to forecast where it is headed. The core premise, developed by Holger Ernst for patent data and by Robert Watts and Alan Porter in their innovation-forecasting fram

Triple Helix Indicators (Mutual Information)

Triple Helix indicators measure the interaction among universities, industry, and government in a knowledge-based innovation system using information theory. Building on the Triple Helix model of Henry Etzkowitz and Loet Leydesdorff, Leydesdorff proposed in 2003 that the three-way mutual information across these instit

Usage Bibliometrics (Downloads and COUNTER)

Usage bibliometrics measures the impact of scholarly works from how often they are downloaded and viewed rather than how often they are cited. Drawing on server and publisher logs standardized through the COUNTER code of practice, it turns raw access events into impact indicators such as the usage factor. The MESUR pro