Venn diagrams have been used by librarians for ages to help users visualize how complex searches work. This is particulalrly true with vast bibliographic databases such as PubMed. In it's default mode, PubVenn takes a complex PubMed search and divides it into its constituent parts. It then searches those disparate parts and shows the piles of citations they return using a proportionally-sized venn diagram.
Every time you enter a PubMed search, the friendly computers at the NCBI work to translate your terms(s) into a carefully codified search, often combining the words that you typed with a series of Medical Subject Headings (MeSH). For example, "death" becomes "death"[MeSH Terms] OR "death"[All Fields]", while "heart attacks and aspirin" turns into the slightly more wordy ("myocardial infarction"[MeSH Terms] OR ("myocardial"[All Fields] AND "infarction"[All Fields]) OR "myocardial infarction"[All Fields] OR ("heart"[All Fields] AND "attacks"[All Fields]) OR "heart attacks"[All Fields]) AND ("aspirin"[MeSH Terms] OR "aspirin"[All Fields])". While it is possible to view this process on PubMed iteslf by peeking in the "search details" box, it can be difficult to visualize just what these terms represent. Expanded subjects mode makes this process explicit.
Please note that the information provided here comes ultimately from the National Center for Biotechnology Information and is subject to the terms listed under their Disclaimer and Copyright notice. While PubVenn will almost always give a good sense of set proportions, plotting intersections onto a two-dimensional plane can be somewhat inexact for any diagram involving more than two sets. If you have any problems, comments or enhancement requests, please contact Ed Sperr at firstname.lastname@example.org.
You can find the source code for this application at GitHub.
Feel free to use this tool as you wish, but if you use PubVenn for publication, I'd appreciate a citation:
Sperr E. PubVenn [Internet]. 2015 [cited your_date_here]. Available from https://pubvenn.appspot.com/
Want to have even more fun with MEDLINE visualizations? Check out Visualizing PubMed.