SPEA H322 Principles of Epidemiology

Searching large multidisciplinary/multi-publication databases requires efficient and effective strategies to obtain a set of manageable and useful search results.

General Strategy:

• Consider keywords and controlled vocabulary
• Create a search statement
• Utilize database features
• Change approaches as necessary

The most difficult part of conducting a good search is not figuring out which buttons to push, but rather, in figuring out which terms to use and how to combine them to find literature that is "on topic."

Generating Keywords:
Start with your health and/or disease condition. Note possible synonyms and variations.

Controlled Vocabulary:
Many databases have some form of controlled or standardized vocabulary. One term is selected as the "preferred" word for describing information and searching. These standardized words and concepts can be called "subject" terms or "descriptors." Words selected for controlled vocabularies are decided by specialists in information science and/or academic disciplines. 

MeSH (Medical Subject Headings) are a controlled vocabulary thesaurus created by the National Library of Medicine and used to index articles for MEDLINE and PubMed. Over 24,000 descriptors are arranged in a hierarchical manner called the MeSH Tree Structures.

Boolean Operators (Combining Keywords & Controlled Vocabulary):
If you put "e coli" into a database search box, you will get thousands of results--and many of these will not be useful for you. Combine keywords and controlled vocabulary together in differing combinations using Boolean Operators (AND, OR) to obtain a more manageable, pointed set of search results.

Use "AND" to Narrow Search (Escherichia coli and epidemiology)
This directs the database to produce records that include all the search terms that were used--all terms and concepts that are entered must be in each of the resulting records. The more search terms used, the more specific and thus narrow the results will be.

Use "OR" to Broaden Search (E. coli or Escherichia coli)
This directs the database to produce records that will include either search term used. The more search terms connected with "or," the broader the results will be.

Truncation, Wildcards, and Phrases:
You can refine searches with truncation. This allows you to search for variant forms of a word (bacteri*). Variations of words can be searched by adding or replacing characters at the end, beginning, or middle of a word with a wildcard (behavio*r). Use quotes ("") to search as a phrase.

In order to search effectively and save time, it is important to become familiar with the database being used. The searching methods vary from database to database; however, most have the following functions.

Basic Search:
Typically, the basic search box only searches one field, which may or may not be predetermined. The basic search is useful to determine how big the collection of articles related to the topic is, which will help in generating search strategies. It is also helpful when doing a known item search, for example when the exact article title is known.

Advanced Searches:
The advanced search function gives more control to the user and allows for a more refined search. Multiple search terms in multiple fields can be searched simultaneously. The advanced search should be used when the collection of interested articles is large and needs to be narrowed. It is also useful when information from more than one field would help in locating an item of interest.

Limits:
Many databases have limits that control the available articles by specified parameters (e.g., date, format, material type, language, or location). This feature is helpful to eliminate records that are outside the selected limits, such as if only review articles are needed or if articles in the last five years are of interest.