Citation Impact

The extent to which a research output, researcher, or venue has been cited by later work, used as a proxy for scholarly influence and measured through a family of metrics that range from raw, unweighted citation counts to field-normalized indicators designed to correct for citation-rate differences across disciplines.

ByCASRAI Editorial Board

· Last updated 18 Jul 2026

Worked examples

Is an instance

A tenure committee reviews an applicant's total citations, h-index, and a field-normalized FWCI score together rather than any single number in isolation.

Is an instance

A funder's grant-portfolio report cites field-normalized citation impact (FWCI or a comparable metric) to compare grantees across disciplines that have very different baseline citation rates.

Citation impact describes how much later scholarship has cited a given paper, researcher, or publication venue. It is one of the oldest and most widely used proxies for scholarly influence, but it is measured through several genuinely different metrics, and conflating them — especially applying a journal-level metric to an individual article or author — is one of the most common errors in research assessment.

Major citation impact metrics

Raw citation counts — the simplest measure: how many times a work has been cited, with no adjustment for field, time, or document type.
h-index — a single number combining an author’s productivity and citation counts, but it is field-, time-, and database-dependent and is cautioned against for hiring and promotion decisions by the Leiden Manifesto and similar responsible-metrics frameworks.
Field-normalized metrics — indicators built specifically to correct for the fact that citation practices vary hugely by discipline, including Field-Weighted Citation Impact (FWCI) and the Relative Citation Ratio (RCR).
Journal-level metrics — a distinct category that describes a venue, not an individual article or author, including the Journal Impact Factor (JIF) and CiteScore. These should never stand in for the citation impact of a specific paper or person.

Citation impact vs. altmetrics

Citation-based measures are a lagging indicator: citations accrue over years as later work is published, reviewed, and formally references the original. Altmetrics capture a faster, broader-audience signal — social media mentions, news coverage, policy citations, downloads — but they measure attention and reach, not scholarly citation, and are a complement to citation impact rather than a replacement for it.

Why field normalization matters

Citation density varies enormously across disciplines: fields with large, fast-publishing communities and long reference lists (some areas of biomedicine, for example) generate far more citations per paper than smaller or slower-publishing fields (many areas of mathematics or the humanities). Raw citation counts and h-index are not directly comparable across fields for this reason, which is exactly why field-normalized metrics such as FWCI and RCR were developed — each expresses a work’s citations relative to a same-field, same-year baseline rather than as an absolute count.

Citation impact is not the same as quality

Responsible-metrics frameworks — including the San Francisco Declaration on Research Assessment (DORA), the Leiden Manifesto, and CoARA — caution that citation counts reflect visibility and use, not correctness, rigor, or importance. Citation distributions are also highly skewed: at the journal level, a small number of heavily cited papers can dominate an average like the Journal Impact Factor, so no single citation-impact number should be read as a standalone verdict on quality without context.

References

Hirsch, J. E. (2005). An index to quantify an individual’s scientific research output. PNAS.
San Francisco Declaration on Research Assessment (DORA), sfdora.org.
Hicks, D., Wouters, P., et al. (2015). The Leiden Manifesto for research metrics. Nature.

Use in your systems

JATS XML <role> element

xml

<role vocab="credit"
      vocab-identifier="https://casrai.org/dictionary/"
      vocab-term="Citation Impact"
      vocab-term-identifier="https://casrai.org/dictionary/term/citation-impact" />

Schema.org DefinedTerm (JSON-LD)

json

{
  "@context": "https://schema.org",
  "@type": "DefinedTerm",
  "@id": "https://casrai.org/dictionary/term/citation-impact",
  "name": "Citation Impact",
  "identifier": "https://casrai.org/dictionary/term/citation-impact",
  "description": "The extent to which a research output, researcher, or venue has been cited by later work, used as a proxy for scholarly influence and measured through a family of metrics that range from raw, unweighted citation counts to field-normalized indicators designed to correct for citation-rate differences across disciplines.",
  "inDefinedTermSet": "https://casrai.org/dictionary/domain/responsible-assessment#set",
  "url": "https://casrai.org/dictionary/term/citation-impact",
  "sameAs": [],
  "license": "https://creativecommons.org/licenses/by/4.0/",
  "publisher": {
    "@id": "https://casrai.org/#organization"
  },
  "dateModified": "2026-07-18T06:30:54",
  "inLanguage": "en"
}