PlumX Metrics and Altmetrics both track online attention to research outputs, but they are not interchangeable: PlumX organises data into five uncombined categories (Citations, Usage, Captures, Mentions, Social Media), while Altmetric.com aggregates sources into a single weighted Altmetric Attention Score. Choosing between PlumX vs Altmetrics for assessment therefore depends on whether an institution needs a granular breakdown or a single comparable number — and on disclosing what each tool does not cover.
Altmetrics, as a category, is the collective term for non-citation indicators of research attention — social media mentions, news coverage, policy citations, blog posts, and readership counts — used alongside, not instead of, traditional bibliometrics.
- What is PlumX Metrics?
- What are Altmetrics and the Altmetric Attention Score?
- PlumX vs Altmetrics: data sources and categories compared
- What coverage gaps should institutions disclose?
- Answer-first Q&A
- Implications for research assessment
What is PlumX Metrics?
PlumX Metrics is an altmetrics service developed by Plum Analytics, now owned by Elsevier and embedded directly into Scopus and SciVal article records. It does not produce a single composite score. Instead, it sorts attention data into five discrete categories: Citations, Usage, Captures, Mentions, and Social Media, displayed as a five-segment “Plum Print” whose circle sizes scale with activity in each bucket.
The University of Waterloo Library notes that PlumX “deliberately does not aggregate their altmetric data sources into a single score” — a design choice that keeps categories separable but makes cross-article ranking harder than with a single number.
What are Altmetrics and the Altmetric Attention Score?
Altmetric.com, part of Digital Science, is the best-known commercial provider of the broader “altmetrics” concept. It compresses attention data from news outlets, blogs, policy documents, X/Twitter, and other sources into a single weighted number — the Altmetric Attention Score — visualised as a multicoloured “donut” where each segment represents a source type.
This single-score design makes Altmetric easier to sort and benchmark at scale across large publication sets, which is why publisher platforms including Wiley and Springer Nature embed the Altmetric badge directly on article pages.
PlumX vs Altmetrics: data sources and categories compared
A 2024 study in Learned Publishing by Rasuli directly tested coverage differences between the two tools and found neither is universally superior: Altmetric.com had the strongest coverage of blogs, news articles, and X/Twitter mentions, while PlumX showed better coverage of Mendeley reader counts. That finding — a real, citable data point — is the clearest evidence that the two tools are complementary, not substitutable.
| Dimension | PlumX Metrics | Altmetric (Attention Score) |
|---|---|---|
| Owner | Plum Analytics, part of Elsevier | Altmetric.com, part of Digital Science |
| Category structure | Five uncombined categories: Citations, Usage, Captures, Mentions, Social Media | Single weighted score plus a source-level breakdown |
| Composite score | None — a five-category “Plum Print” visual | Yes — the Altmetric Attention Score, one number |
| Documented strength (Rasuli, 2024) | Mendeley reader counts | Blogs, news, and X/Twitter mentions |
| Primary institutional integration | Scopus and SciVal article records | Altmetric Explorer; publisher platforms (Wiley, Springer Nature) |
Both tools also include a distinct Citations dimension in their scope: PlumX’s Citations category explicitly folds in Scopus citation counts alongside patent, clinical, and policy citations, while Altmetric treats citation data as a separate, secondary layer rather than a core category.
What coverage gaps should institutions disclose?
Neither tool captures the full universe of research attention, and both have known blind spots that assessment reports should state explicitly rather than imply away:
- Platform coverage is uneven. The Rasuli (2024) comparison shows each tool systematically under-represents sources the other captures better, so a low score on one platform does not mean low attention overall.
- Absence of a score is not absence of impact. An article with no PlumX or Altmetric activity may simply lack a DOI-linked record, an institutional repository deposit, or public discussion in the tracked window — not lack of scholarly value.
- Composite scores obscure source mix. A single Altmetric Attention Score can be driven almost entirely by one viral social post; disclosure should note the underlying source breakdown, not just the headline number.
- Gaming and reproducibility risk. NISO’s Recommended Practice RP-25-2016, the output of its Alternative Assessment Metrics initiative, explicitly flags data-quality, persistent-identifier, and manipulation-resistance requirements that altmetrics providers and institutions using them should meet.
- Metrics indicate attention, not quality. INORMS’s SCOPE framework for responsible research evaluation stresses that any metric — including altmetrics — should be interpreted only against the specific purpose it was chosen to serve, not treated as a proxy for research quality.
Research administrators compiling assessment dossiers should state which tool was used, the date the score was pulled, and which categories were included — omitting this context is the most common disclosure failure institutions make when citing either platform.
Answer-first Q&A
Is Altmetric reliable?
Altmetric is reliable as an indicator of online attention, not as a quality measure. Because it harvests data from many external, non-standardised sources, coverage varies by discipline and platform, so scores should be interpreted alongside citation data rather than in isolation, per NISO’s altmetrics recommended practice.
What is the difference between altmetrics and bibliometrics?
Bibliometrics measure scholarly interest through formal citation counts in indexed literature, while altmetrics track online engagement — downloads, mentions, shares, and discussion — across academic and public channels. The two measure different things and are designed to complement, not replace, each other.
Is PlumX Metrics free?
The PlumX artifact widget is free for any digital object with a DOI and can be embedded on repository or publication pages at no cost. Full institutional dashboards and analytics through Scopus/SciVal, however, require a paid Elsevier subscription.
What is the difference between Altmetric and PlumX?
Altmetric compresses attention into one weighted Attention Score with a donut visual, while PlumX keeps five categories separate in a Plum Print graphic with no combined number. The practical difference is aggregation: one number for quick ranking versus five categories for granular review.
Implications for research assessment
As institutions build multi-metric assessment dashboards, the choice is rarely PlumX or Altmetric — most research-intensive universities license both, because Scopus-indexed institutions already have PlumX embedded and many also subscribe to Altmetric Explorer for its stronger media and policy tracking. What matters for defensible assessment practice is documenting scope: which categories were pulled, on what date, and which known coverage gaps apply.
Frameworks such as INORMS’s SCOPE model give research administration teams a structure for that documentation, tying metric choice back to the specific evaluative purpose rather than treating either tool’s output as a self-evident ranking. Consult the CASRAI Dictionary for definitions of related terms such as citation, altmetrics, and bibliometrics when drafting assessment policy language.