Library Guides: Meta-analyses: Identify keywords

Identifying keywords

It is important to find all the relevant keywords for the topic to ensure the search is comprehensive by identifying

different spellings, tenses and word variants of keywords
synonyms
related concepts

There are many ways to locate these terms, including background reading, dictionaries, regular and database thesauri or subject headings and text mining tools. The process of searching will also help identify more terms.

Comprehensive vs precise

There needs to be a balance in searching between making the search comprehensive enough to encompass everything on the topic and precise enough to only capture those results that are specifically relevant.

Both approaches have advantages and disadvantages

Type of Search	Comprehensive	Precise
Advantages	Broad search finds everything on topic	Specific to topic so results are more relevant
	Lessens chance of missing relevant papers	Easier to discard irrelevant results
Disadvantages	Too much information to process easily	Not enough results
	Many irrelevant results to discard	Many relevant papers missed as topic too narrow

Increasing the comprehensiveness (or sensitivity) of a search will reduce its precision and will retrieve more non-relevant articles.

Using text mining to identify keywords

Text mining will help identify how often terms come up in the literature and help identify other related terms and subject headings that have not been considered or thought of as being useful.

Text mining is a process used to look at large amounts of text and find relationships in the results by using computer programs designed to extract and analyse this data.

It is used to categorise information and identify trends and patterns which can be done across large documents or multiple sources (or both).

Methods

1. Mining for terms
Use these tools to find alternate search terms that are related by identifying how often keywords appear and which other terms appear with them by number of occurrences.

Ovid Reminer Tool
Upload a file of Medline results saved as a csv or excel file to analyse for term occurrence. Available fields include -Author(s), Title, Source, Subject Headings, Abstract and Publication Type. Note that Embase and CAB Abstracts are not available through JCU so cannot be used, and PsycINFO is not compatible with the Ovid Reminer Tool.
PubReminer
Enter search terms and click Start PubReminer button. Note boolean search connectors should not be included in the search.
Yale MeSH Analyzer
Enter a list of PubMed (PMID) numbers to see a list of MeSH headings and author keywords. Results can be downloaded to Excel for analysis.

2. Mine within the text
Locate terms within blocks of text (e.g. an article) to find word patterns and frequency. More frequent words are more likely to be relevant to the topic.

Termine
Enter a block of text or a file and the Termine system will analyse the text to highlight key terms.
WriteWord phrase frequency
Enter a block of text to count the frequency usage of phrases in the work. A single word frequency counter is also linked from this page.
MeSH on Demand
MeSH on Demand identifies MeSH® terms in the submitted text (abstract or manuscript). MeSH on Demand also lists PubMed similar articles relevant to the submitted text.
JSTOR Text Analyser
Upload a document into the JSTOR Text Analyser and it will analyse the text to find the key topics and terms used. It then priortises these terms and uses the ones it deems most important to find similar content in JSTOR. Refine the search results, by adding, removing or adjusting the priority of terms.
Voyant: See through your text
Voyant Tools is a web-based reading and analysis environment for digital texts. It provides text analysis and some visualisation tools.

3. Use visualising tools
These tools create word clouds related to search terms

Coremine Medical
Coremine presents search results as a graphic network that describes relationships discovered through text-mining for a huge range of biomedical terms, including Medical Subject Heading, Gene Ontology, Pharmaceutical, Herbal medicine and Chemical as well as Gene and Protein terms. Free registration required to use.
PubVenn
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 to show the amount published on any given topic and the overlap between different concepts.
Vizit
Vizit is a visual bibliographic search tool that presents results as a visual network of related terms and then links to the relevant literature.
Carrot2
Carrot2 is an Open Source Search Results Clustering Engine. It can automatically organize small collections of documents into thematic categories and displays in folders, circles or foam trees to visualise the results.

These are just some of the tools available for mining text that are available on the web. There is also both commercial and free software that can be downloaded and installed. The web pages linked below have lists of yet more tools.

Meta-analyses

Identifying keywords

Comprehensive vs precise

Type of Search

Comprehensive

Precise

Advantages

Disadvantages

Using text mining to identify keywords

Text mining will help identify how often terms come up in the literature and help identify other related terms and subject headings that have not been considered or thought of as being useful.

Methods

Further reading: