Journal and Research Metrics Classification
| Metric | Database/Source | Time Window | Description | Strengths | Limitations |
|---|---|---|---|---|---|
|
Impact Factor (IF)
IF = (Citations in year N to articles from years N-1 & N-2) / (Number of articles in N-1 & N-2)
|
Web of Science | 2 years | Citations received / Papers published | Widely recognized, standardized | Field bias, manipulation possible |
|
CiteScore
CiteScore = (Citations in year N to articles from N-1, N-2, N-3) / (Number of articles in N-1, N-2, N-3)
|
Scopus | 3 years | Citations received / Papers published | Longer window than IF, transparent | Newer metric, less established |
|
SCImago Journal Rank (SJR)
SJR ≈ Weighted citations / Number of articles (weight considers source prestige)
|
Scopus | 3 years | Weighted citations considering source prestige | Quality-weighted citations | Complex calculation |
|
Source Normalized Impact per Paper (SNIP)
SNIP ≈ Raw citations / Field citation potential
|
Scopus | 3 years | Corrects for field citation differences | Field-normalized | Complex interpretation |
| Eigenfactor Score | Web of Science | 5 years | Network-based journal influence | Considers citation network | Difficult to interpret |
| Article Influence Score | Web of Science | 5 years | Average influence per article | Per-article focus | Low scores hard to interpret |
| Immediacy Index | Web of Science | 1 year | Speed of citation after publication | Measures immediate impact | Very short window |
|
h5-index
h5 = max { h | h articles in last 5 years have ≥ h citations each }
|
Google Scholar | 5 years | h-index for journal’s recent articles | Combines productivity and impact | Google Scholar coverage issues |
|
h5-median
h5-median = median citations of h5-core articles
|
Google Scholar | 5 years | Median citations of h5-core articles | Complements h5-index | Limited interpretability |
| Metric | Formula/Definition | Strengths | Limitations | Best Used For |
|---|---|---|---|---|
|
h-index
h = max { i | paper i has ≥ i citations }
|
h papers with ≥h citations each | Simple, combines productivity & impact | Favors older researchers, field-dependent | Overall career assessment |
|
i10-index
i10 = number of papers with ≥10 citations
|
Papers with ≥10 citations | Easy to understand | Arbitrary threshold | Productivity measure |
|
g-index
g = max { g | sum of top g citations ≥ g² }
|
Largest g where top g papers have ≥g² citations | Sensitive to highly cited papers | More complex calculation | Impact of top papers |
|
m-index
m = h-index / years since first publication
|
h-index / years since first publication | Age-normalized | Penalizes career breaks | Career stage comparison |
|
e-index
e = √(excess citations beyond h-core)
|
√(excess citations beyond h-core) | Captures citation surplus | Complex interpretation | Citation distribution analysis |
|
A-index
A = mean citations of h-core papers
|
Average citations of h-core papers | Average impact of core papers | Requires h-index calculation | Core paper quality |
|
R-index
R = √(total citations in h-core)
|
√(citations of h-core papers) | Considers total impact | Square root transformation | Balanced impact measure |
| Category | Metric | Source | What It Measures | Applications |
|---|---|---|---|---|
| Altmetrics | Altmetric Score | Altmetric.com | Social media, news, policy mentions | Public engagement, societal impact |
| Usage Metrics |
Downloads
Downloads = Count of full-text downloads or views
|
Publishers | Article downloads/views | Reader interest, accessibility |
| Usage Metrics | PlumX Metrics | Plum Analytics | Usage, captures, mentions, citations | Comprehensive impact view |
| Social Media | Tweet Count | Various platforms | Social media mentions | Public discourse impact |
| Policy Impact | Policy Citations | Policy databases | Government/policy document citations | Policy relevance |
| News Impact | News Mentions | News aggregators | Mainstream media coverage | Public awareness |
| Database | Primary Metrics | Coverage | Strengths |
|---|---|---|---|
| Web of Science | Impact Factor, Eigenfactor, Article Influence | Selective, high-quality journals | Established, rigorous |
| Scopus | CiteScore, SJR, SNIP | Broader than WoS | Comprehensive coverage |
| Google Scholar | h5-index, h5-median | Very broad, includes grey literature | Comprehensive, free access |
| Microsoft Academic | Field-normalized metrics | Broad coverage | AI-powered analysis |
| Dimensions | Field Citation Ratio, Relative Citation Ratio | Comprehensive | Policy and patent linkage |
| Index Type | Examples | Purpose | Calculation Method |
|---|---|---|---|
| Field-Normalized |
Crown Indicator
Crown Indicator = Citations / Average citations in field
|
Cross-field comparison | Percentile-based ranking within field |
| Field-Normalized |
PP(top 10%)
PP(top 10%) = % of papers in top 10% most cited in field
|
Cross-field comparison | Percentile-based ranking within field |
| Time-Normalized |
Contemporary h-index
Each paper weighted by (4 / (current year – publication year + 1))
|
Account for publication timing | Time-weighted calculations |
| Collaborative |
Fractional counting
Each author receives 1/nth credit if n co-authors
|
Account for collaboration | Weighted by author contribution |
| Quality-Weighted |
Weighted h-index
Weighted h-index = h-index weighted by journal prestige of each paper
|
Emphasize journal quality | Citations weighted by journal prestige |
| Composite | Integrated metrics | Holistic assessment | Combination of multiple indicators |
| Purpose | Recommended Metrics | Avoid |
|---|---|---|
| Journal Selection | Impact Factor, CiteScore, SJR | Single metric decisions |
| Researcher Evaluation | h-index + field context | h-index alone |
| Cross-Field Comparison | Field-normalized metrics | Raw citation counts |
| Early Career Assessment | m-index, recent publications | Career-long metrics only |
| Societal Impact | Altmetrics, policy citations | Traditional citations only |
| Funding Decisions | Multiple complementary metrics | Any single indicator |