Disagreeing with a PubMed Instructor about MeSH
Rachel (at Women’s Health News) wrote yesterday about her week-long course in biomedical informatics in a post wonderfully titiled “Dispatches from Nerd Camp.” She writes:
…our PubMed instructor declared, “I’m over the whole MeSH thing,” in the context of explaining that she thinks it’s completely unnecessary to know about and too hard to use.
[snip]
The instructor suggested that keyword searching is always just fine because it will map to MeSH anyway. This is often true. However, I did a keyword search on “HRT” (a popular topic that most adult humans would understand) and discovered that this does not map to the “Hormone Replacement Therapy” MeSH, and returns a pretty poor set of search results. Discuss.
[My emphases]
Rachel’s instructor is right that using MeSH effectively can be difficult, but many good and useful things are not immediately easy, so I’d categorically dismiss this as a legitimate reason to be “over MeSH.”
The other reasoning that Rachel reports was presented by the instructor is that “keyword searching is always just fine because it will map to MeSH anyway.”
But as Rachel points out, it isn’t always just fine. Sometimes, it is downright inadequate.
Where PubMed fails to map
Check out the search that Rachel describes, searching for HRT in PubMed. Because PubMed doesn’t map HRT to the appropriate MeSH term, it defaults to a keyword search, producing a number of hits in the first 20 results that really aren’t about hormone replacement therapy. So it seems clear that Rachel’s instructor overestimates how effective PubMed’s automatic mapping to MeSH terms is. (I’m not faulting PubMed for this- this mapping must be incredible work to maintain and update.)
“Unnecessary to know about?”
For a moment, we’ll embrace as true the premise that PubMed usually maps as we’d like and reveals the results we’re looking for. If we don’t know how to utilize MeSH, how will we get what we need on the occasions where PubMed doesn’t do this?
Improving Keyword Searching in PubMed
That isn’t to say that keyword searching couldn’t be made much more effective in PubMed. Try searching for “HRT” (without the quotes) at ReleMed and page through the first 25 hits (I stopped at 25), you’ll find they’re all about hormone replacement therapy, despite the fact that the NLM hasn’t mapped “HRT” to the relevant MeSH term(s). ReleMed does two things that are awesome. First, it uses UMLS to translate “HRT” into (hormone replacement therapy) OR (hormone replacement therapies) OR hrt OR (hormone replacement rx)1
Secondly, it intelligently sorts the results by relevance (details here).
I hope that the NLM will either buy the technology from ReleMed or develop a similar capability to do the same thing in PubMed, something like this:
(Previously suggested here).
MeSH + PubMed = Best possible results
Even so, the ReleMed search for HRT still isn’t as effective as executing a search in PubMed like “hormone replacement therapy”[majr]
Over MeSH?
No. Not by a long shot- and I wouldn’t want a medical librarian who found MeSH “too hard to use” doing literature searches for our library’s patrons. Our clinical patrons need and deserve the best possible results we can deliver and that takes an understanding of MeSH. MeSH is necessary, it is not too hard to use, and keyword-to-MeSH mapping doesn’t always work as we’d hope.
Unless I’m wrong
This seems pretty clear to me, but I’ve only been working in a medical library for less than two years. I’d love to hear more experienced medical libraryfolk weigh in on the topic. Please consider leaving a comment or blogging about it yourself.
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