18 February 2011

mish mash MeSH: What your Librarian's talking about & how to construct a better search

So you're doing a topic search in one of your Library's databases: you enter a term and are asked to choose between keyword or MeSH term but what's this gobblygoop 'MeSH' and why is it relevant to your search?  Well let's break it down.
MeSH versus Keyword

Keyword: When searching by keyword you are essentially searching the articles for any instance of that word.  For example, if you enter the term 'Arm' into Medline and search by keyword your results will include all the articles within the database that mention the word 'Arm' anywhere in the article. In other words you'll get articles relating to arms (as in the human appendage) but you'll also be getting back irrelevant articles e.g. 'Arm yourself against the common cold'.  Bottom line: keyword searches can result in a lot of unwanted results.  Of course it may still be useful but I would recommend using keywords only if there is no MeSH term available.  Of course I still haven't defined MeSH!

MeSH:  MeSH stands for Medical Subject Heading and are used for indexing biomedical articles for both the PubMed and Medline Databases.  When published, articles are assigned MeSH headings by staff  at the National Library of Medicine.  Essentially, they're a controlled 'label' assigned to the journal.  If I were to do my same search with the term "Arm" and choose the MeSH option instead of the keyword my results will be contained to articles relating only to the human appendage or 'upper extremity' (which is where the 'arm' heading falls under in the MeSH hierarchy).

Let's look at the difference!

Database: Medline
Search term: Arm
Keyword search only: 87,901 results
MeSH search: 23,249 results
Difference: 64,654 fewer results with MeSH

Though 23,249 is still a huge result, when you start combining it with other terms similarly narrowed with MeSH you end up with much more tangible results than a keyword-only search.  Talk to your Librarian if you want some more information/help with MeSH or any literature searching strategies!

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