Every early-career researcher is eventually asked for a number — an impact factor, a quartile, an h-index — usually by someone who does not specify which. The metrics measure genuinely different things, and using the wrong one in a promotion file is an avoidable error.
What is a journal impact factor?
The average number of citations received in one year by the articles a journal published in the previous two years. Clarivate calculates it, publishes it annually in the Journal Citation Reports, and only journals in SCIE or SSCI have one at all.
A 2025 impact factor of 4.2 therefore means articles published in 2023 and 2024 averaged 4.2 citations during 2025. It is a property of the journal, never of your paper.
What is a good impact factor?
It depends entirely on the field, and comparing across fields is meaningless. In parts of mathematics a factor above 2 is excellent; in parts of clinical medicine and cell biology, 10 is unremarkable.
Citation behaviour differs by discipline — field size, how quickly work gets cited, and whether the field publishes mainly in journals or conferences all move the number. This is precisely why quartiles exist.
What do Q1 and Q2 mean?
They are a journal's rank within its own subject category, divided into four equal parts: Q1 is the top 25% of journals in that category, Q2 the next 25%, and so on. Because the comparison happens inside a field, Q1 means something consistent across disciplines in a way a raw impact factor does not.
One caution: a journal listed in several categories can be Q1 in one and Q3 in another. When someone asks for a Q1 publication, they usually mean Q1 in the category matching your work.
What is CiteScore, and how is it different?
CiteScore is Scopus's equivalent metric, calculated over a four-year window instead of two and covering every journal in Scopus — including the many that have no impact factor at all.
The longer window makes it steadier year to year and generally more useful where citations accumulate slowly, as in much of the social sciences and humanities.
Does the h-index measure a journal or a person?
Usually a person, although it can be calculated for anything with a publication list. Your h-index is the largest number h such that you have h papers each cited at least h times — an h-index of 12 means twelve papers with at least twelve citations each.
It deliberately rewards sustained output over a single famous paper, which is both its strength and its weakness. It also rises with career length, so comparing a postdoc's h-index with a professor's mostly measures time elapsed.
| Metric | Measures | Source |
|---|---|---|
| Journal Impact Factor | A journal, two-year window | Clarivate (JCR) |
| Quartile (Q1–Q4) | A journal, ranked within its field | Clarivate or Scopus |
| CiteScore | A journal, four-year window | Scopus |
| h-index | A researcher's cumulative record | Scopus, Web of Science, Google Scholar |
Should you choose a journal by its impact factor?
No — choose by scope fit first, then use metrics to rank the journals that already fit. A paper sent to a high-impact journal outside its scope is desk-rejected within days, costing weeks and gaining nothing.
The highest-value decision is finding the best-ranked journal whose readership your paper genuinely belongs to. That trade-off sits at the centre of the publication process, and it is where we spend most of our time with authors.
