How to Extract Data from Scopus, WoS, and PubMed for Bibliometric Analysis
Did you know that 80% of bibliometric analysis failures don’t happen during mapping — they happen during data extraction? A wrong file format, incomplete metadata, or violated export limits can make VOSviewer and Biblioshiny reject your data — or worse, produce misleading maps. The principle is simple: garbage in, garbage out. This article guides you through extracting data from the three giant databases — Scopus, Web of Science (WoS), and PubMed — in formats compatible with popular bibliometric tools. If you don’t want to spend hours managing export limits and format conversions, the Corvexum team is ready to prepare a clean, analysis-ready dataset for you.
Step 0: Build a Solid Search String
Before touching the export button, make sure your query is mature. Use Boolean operators (AND, OR, NOT), quotation marks for exact phrases, and asterisks for truncation. Example: ("electric vehicle*" OR "ev adoption") AND ("consumer behavior" OR "purchase intention"). For PubMed, leverage MeSH terms for greater precision. Record and save your final search string — it is mandatory to report in your methodology section and reviewers will ask for it.
Extracting from Scopus (2,000 per Export Limit)
Scopus limits a single export to a maximum of 2,000 documents. If your results total 5,600 documents, you need 3 exports (1-2000, 2001-4000, 4001-5600). The steps:
- Run the search, then select all results and click Export.
- Choose the CSV format — the friendliest for Bibliometrix/Biblioshiny and VOSviewer.
- Tick all metadata blocks: Citation information, Bibliographical information, Abstract & Keywords, and References. Skipping References means losing co-citation and bibliographic coupling capabilities.
- Repeat for the next range, then save with sequential names (scopus_part1.csv, etc.).
Extracting from Web of Science (1,000 per Export Limit)
WoS Core Collection limits exports to 1,000 records per download. Use the Export → Excel / Plain Text / Tab-delimited menu. For bibliometric analysis, select Full Record and Cited References content. Both Plain Text (.txt) and Tab-delimited (.txt/.dat) formats are recognized by bibliometrix’s convert2df function. Don’t forget: WoS stores cited references most neatly of the three, making it superior for co-citation analysis and historiographs.
Extracting from PubMed (Free, but With Caveats)
PubMed is heaven for health and biomedical fields, and completely free. Use the Save / Send to → File button, then choose the PubMed or MEDLINE format that is directly compatible with bibliometrix. Download limits reach 10,000 records per session. But note two major limitations: PubMed does not provide cited references and has no built-in citation metrics. Solutions: combine with Europe PMC or OpenAlex for citation data, or use the NCBI E-utilities API for programmatic large-scale extraction.
Merging & Cleaning the Dataset
Once all files are collected, it’s consolidation time. In R, bibliometrix’s convert2df() function can merge Scopus/WoS files while performing automatic deduplication. Best steps:
- Merge files per database first, then align column structures.
- Remove duplicates based on DOI or title (tools: bibliometrix, or Rayyan for manual checks).
- Check completeness of key fields: Authors, Title, Year, Source, Keywords, References. Empty fields will disable certain analysis menus.
- Save the final dataset as a .RData object or master CSV — this is your project’s most valuable asset.
🎯 Which Database Should You Choose?
- Engineering, social sciences, multidisciplinary? → Scopus (widest coverage, 80+ million records).
- Need strong co-citation & historiograph? → WoS (neatest cited references).
- Medical/biomedical field, zero budget? → PubMed + Europe PMC/OpenAlex.
- Q1-class bibliometric study? → Use at least two databases and report the comparison — a major plus in reviewers’ eyes.
🚀 Don’t Want to Deal With Export Limits & Format Conversions?
Data extraction looks trivial, but a small mistake at this stage corrupts the entire analysis downstream — and fixing it means redoing all the work from scratch. Your time is too valuable to spend downloading files part 1 through part 5 while anxiously fearing omissions. The Corvexum team is ready to prepare a perfect data foundation:
- ✅ Boolean search string design + validation with a research librarian
- ✅ Complete Scopus/WoS/PubMed extraction including all export-limit parts
- ✅ Deduplication, metadata cleaning, and master dataset consolidation
- ✅ Ready-to-use files for VOSviewer, Biblioshiny, or CiteSpace + extraction log for methodology
Or email: corvexum@gmail.com | Visit: corvexum.com/
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