Impact Factor (IF)
Published annually by Clarivate in JCR, IF measures average citations per article over the preceding two years. It is a journal metric, not an article or author metric.
Q1–Q4 Rankings
- Q1: Top 25% by IF — most prestigious.
- Q2: 25–50th percentile
- Q3: 50–75th percentile
- Q4: Bottom 25%
H-Index
A researcher has h-index=15 when 15 papers have each been cited at least 15 times. Rewards both productivity and citation impact.
Limitations of All Metrics
Citation patterns vary enormously by field. Review articles attract more citations than primary research. Use metrics as one input among many — never the only criterion.