Map types
In short: SciNodes builds six kinds of research map from your corpus. Each one links items for a different reason. Citation, Co-citation and Bibliographic Coupling maps use reference lists. Co-authorship maps use author lists. Keyword Co-occurrence and Term Co-occurrence maps use the words in your publications. Choose the type that matches your question, then choose a unit of analysis: publications, venues, authors, organizations, countries, keywords or terms.
Which map answers my question?
| Your question | Map type | Unit |
|---|---|---|
| What are the main topics and themes here? | Term Co-occurrence or Keyword Co-occurrence | Terms / Author Keywords |
| Which publications form the intellectual foundations of this field? | Co-citation | Cited Publications |
| Which schools of thought exist? | Co-citation | Cited Authors |
| What are the current research fronts? | Bibliographic Coupling | Publications |
| Who cites whom, and how does influence flow? | Citation | Publications or Authors |
| Who works with whom? Which research groups exist? | Co-authorship | Authors |
| Which institutions or countries collaborate? | Co-authorship | Organizations / Countries |
| Which journals and conferences talk to each other? | Citation, Co-citation or Bibliographic Coupling | Venues / Cited Venues |
If you're not sure, ask a question instead. SciNodes recommends a map for it. See Create a map from a question.
The six types
Citation
"Map of direct citation links between entities." Two items are linked when one cites the other within your corpus. Use it to follow how ideas flow and to spot heavily cited hubs.
- Units: Publications, Venues, Authors, Organizations, Countries
- Edges are: citations
- Clusters are: Research Community (publications), Disciplinary Cluster (venues), Scholarly Network (authors), Institutional Network (organizations), Regional Cluster (countries)
- Needs reference data. See Empty maps and reference data.
Co-citation
"Map of entities cited together by others." Two items are linked when publications in your corpus cite them together. The more often they're cited together, the stronger the link. The nodes are the publications, authors or venues your corpus cites, so they can include classics that aren't in your corpus. Use it to find a field's intellectual base and its schools of thought.
- Units: Cited Publications, Cited Venues, Cited Authors, Cited Organizations, Cited Countries
- Edges are: co-citations
- Clusters are: Intellectual Base, Field, School of Thought, Institutional Base, Regional Base
- Needs reference data.
Bibliographic Coupling
"Map of entities sharing common cited publications." Two items are linked when they cite the same publications. Recent publications can be coupled straight away, without waiting to be cited, so this map shows research fronts: what people are working on now.
- Units: Publications, Venues, Authors, Organizations, Countries
- Edges are: shared cited publications
- Clusters are: Research Front, Field Front, Scholarly Front, Institutional Front, Regional Front
- Needs reference data.
Co-authorship
"Map of entities that have published together." Two authors, organizations or countries are linked when they appear on the same publication. Use it to find research groups, collaborators and collaboration patterns between institutions or countries.
- Units: Authors, Organizations, Countries
- Edges are: collaborations
- Clusters are: Research Group, Institutional Network, Regional Cluster
- Extra settings in Expert Mode: Merge name variants and Author cut-off. See Expert Mode.
Keyword Co-occurrence
"Map of terms appearing together in publications." Two keywords are linked when they're assigned to the same publication. Use it to see a field's topics through the keywords authors and indexers chose.
- Units: Author Keywords, Index Keywords, MeSH Terms (medical subject headings, for biomedical corpora)
- Edges are: co-occurrences
- Clusters are: Topics
Term Co-occurrence
"Map of terms from titles, abstracts and keywords appearing together." SciNodes extracts terms from the sources you choose, then links terms that appear in the same publication. It works even when publications have no keywords, so it's the default first map: every new project builds an Initial Map of this type.
- Term Sources: any combination of Title, Abstract, Author Keywords, Index Keywords and MeSH Terms. The automatic Initial Map uses Title, Author Keywords and Index Keywords.
- Edges are: co-occurrences
- Clusters are: Topics
- Extra settings in Expert Mode: phrase length, minimum term length and stemming.
What every map has in common
- Nodes are the items (publications, authors, terms and so on). Node size shows a measure such as citation count or number of links. Which measure depends on how you created the map, and some maps open with every node the same size (Unweighted). Change it any time under Node Config → Weightage. See Reading a map.
- Edges are the links. Thicker edges mean stronger links.
- Clusters are groups of closely linked nodes, each drawn in its own color. SciNodes names each cluster with a term that fits the map type, for example "Topic" or "School of Thought".
- A map uses the whole corpus, or a corpus slice you choose when you create it.
FAQ
What's the difference between co-citation and bibliographic coupling?
Co-citation links two items that are cited together by later publications. It looks backward at foundations. Bibliographic coupling links two items that cite the same earlier publications. It looks at current work. Use co-citation for the intellectual base and coupling for research fronts.
Why is my citation map empty?
Citation, co-citation and bibliographic coupling maps need reference lists. Publications imported from the catalog don't include them until you run Fetch reference data once for the project. See Empty maps and reference data.
Which map should I make first?
Start with the automatic Initial Map (term co-occurrence) to see the main topics. Then ask a research question in the Map queries bar and SciNodes will recommend a map type.
Can I change a map's type after it's built?
No. Create a new map with the type you want. Your earlier map stays as it is.