impact factor
nounPronunciation: /ˈɪmpækt ˈfæktər/
Also written as: IF
A metric that measures the average number of citations received by articles published in a journal during a specific time period.
Full Definition
Impact factor is a quantitative measure used to evaluate the relative importance and influence of academic journals within their respective fields. Calculated annually by Clarivate Analytics, it represents the average number of times articles published in a journal during the two preceding years have been cited in the current year. The metric serves as a proxy for journal prestige and is widely used in academic evaluation, tenure decisions, and funding assessments. However, it has limitations and should be interpreted alongside other quality indicators, as it can vary significantly across disciplines and may not reflect individual article quality.
Plain English
A number that shows how often articles from a particular journal get referenced by other researchers, which helps indicate how important or influential that journal is.
In Editorial Context
A key performance metric that influences editorial strategy, author submission decisions, and journal positioning within the competitive academic publishing landscape.
Etymology & History
Developed by Eugene Garfield at the Institute for Scientific Information to help librarians make journal subscription decisions and researchers identify important publications.
Initially a library tool, it evolved into a primary metric for evaluating journal quality and researcher performance, despite growing criticism of its misuse.
Usage
"Academic Medicine's impact factor has steadily increased over the past five years, reflecting the growing influence of medical education research."
Usage note: Should not be used to evaluate individual articles or researchers; represents journal-level, not article-level, impact
Context: journal evaluation, academic assessment, publishing strategy, research metrics
Region: international
Style guide notes: Chicago Manual capitalizes when referring to Thomson Reuters' specific metric, lowercase for general concept, typically not hyphenated
In Context
- "The journal's impact factor increased from 3.2 to 4.1 following its inclusion in high-visibility databases."
- "Editorial decisions should not be based solely on impact factor considerations but on scientific merit."
- "The impact factor calculation includes citations from the previous two years divided by citable articles published."
Also known as
Don't confuse with
H-index measures individual researcher impact, while impact factor measures journal impact; citation count refers to individual article citations
Common mistake: Using impact factor as sole measure of journal quality, comparing impact factors across different disciplines, confusing journal impact factor with article-level metrics
Related Terms
Broader term: bibliometrics
Frequently Asked Questions
How is journal impact factor calculated?
Impact factor equals citations in current year to articles published in the previous two years, divided by the total number of citable articles in those two years.
Why shouldn't impact factor be used to evaluate individual articles?
Impact factor reflects journal-level citation patterns, not individual article quality, and citation distributions within journals are highly skewed.
What are alternatives to impact factor for measuring research impact?
Alternative metrics include h-index, article-level citations, altmetrics, and field-normalized indicators that account for disciplinary differences.
Why Test Candidates on This?
Critical for understanding journal positioning, competitive analysis, and institutional reporting in academic medical publishing
Required skill level: Mid