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Searching for scientific information: Medical Sciences: 4. Searching effectively

To ensure you get meaningful and relevant search results you need to have a search strategy. Research databases don't understand the details of your search topic, so you'll need to prepare a strategy to make sure that you identify all the relevant information on your topic. Having a strategy will also help you recall a manageable number of relevant search results.

Planning a search strategy is a three step process:

1. Identify search terms and any alternative terms for your key concepts

2. Combine your search terms

3. Use search techniques to enhance your search

1. Identify your search terms

Once you have identified your main search concepts, you'll need to identify keywords for each of the concepts. As part of this step, you should consider synonyms and alternative terms to ensure you don't miss vital research papers.

Think carefully about suitable keywords and synonyms (alternative words that have a similar meaning) that will enable you to find manageable amounts of relevant material - not so many results that they are unmanageable and cause information overload, or so few that you retrieve insufficient information for your needs.

Searching on the wrong keywords can result in:

  • Finding little or no relevant information
  • Finding too much information

For example: If you are searching for evidence on (cell) isolation, you should also use alternative terms as keywords such as separation

This video explains the process of mapping out keywords


When you are searching the global literature think about differences in spellings and terminology, and incorporate alternatives into your search strategy. 

For example:   tumour (British spelling)  vs. tumor (American English spelling) 


Have acronyms or abbreviations been used in the sources you have read? 

These can be included in your search terms in order to find matching results. 

For example: Hemoglobin A1C​ and/or HbA1c

If you are searching across long time periods, remember that terminology changes over time. New words appear, others change meaning so be prepared to reflect this in your search strategy.

For example:  tweet or twitter has a dual meaning: 

  1.  posting a short message to the Twitter social media platform
  2.  bird calls or short sharp sounds

2. Combine your search terms

Once you have identified your keywords, there are some useful techniques you should know to help you search most effectively.

It is possible to use a number of different keywords or search terms in a single search, by using operators. Operators link your search terms and define the relationship between them.

This enables more accurate searching and therefore more relevant results being returned. It also saves you time as you don't have to carry out numerous similar searches where just one or two search terms are changed each time.

The three most commonly used operators are ANDORNOT.  These are known as Boolean operators. They can be used to broaden or narrow a search and to exclude unwanted search terms and concepts.

This short video explains in more detail:

Need a refresher on basic searching and using AND/OR? Take a look at the Medical Sciences: finding and using library resources for assignments tutorial

Use AND to narrow your search.

Using AND between your search terms narrows your search as it instructs the database that all your search terms must appear (in any order).

For example: 

White blood cell AND peripheral blood AND isolation

Because all search terms must be present, using AND makes the search more focused. In some (but not all) databases and search engines the AND is implied so if you enter multiple words the database will search for results which contain all/both words.

Use OR to broaden your search.

Using OR between search terms broadens your results as any or all of your search terms can be present.

For example: 

White blood cell OR luekocytes OR neutrophils

Isolation OR separation

It is extremely useful for finding synonyms or related concepts. Using OR enables you to carry out a number of similar searches in one go, saving you time.

3. Remember to use search techniques to improve your search

You can use search techniques to help improve your searching. By applying these techniques, you can increasereduce or improve the relevancy of your search results, making it easier to access to the right materials. For more, see the Search tips guide.

Truncation is a technique that broadens your search to include various word endings and spellings. This saves you time and means you don't need to enter several different search terms with the same root.

To use truncation, enter the root of a word and put the truncation symbol at the end.

The database will return results that include any ending of that root word.

Tip: The asterisk * symbol is most commonly used for truncation. However, check out the help guide in the database you are using as  !, ?, or # may also be used.

For example:

child* will find child, childrenchildlikechildhood etc.

Radiograph* will find radiography, radiographer, radiographers, radiographic etc.

Use it with care to avoid finding too many alternatives.

Wildcards are similar to truncation but they are used to substitute for a single letter or no letter in a word.

They are useful for irregular plurals and for British/American English spellings.

They broaden your search by including variant word spellings.

The question mark symbol is most commonly used. However, check out the help information on the database you are using as  ! , *, or # may also be used. 

For example:

wom?n will find woman and women

optimi?ation will find optimisation and optimization

model?ing will find modeling and modelling

Phrase searching is the most limiting technique as it is used to specify that your terms must appear next to each other, and in the order you specify.

Phrase searching is commonly achieved by surrounding your phrase with quotation marks.

Always check the Database Help screens, as some databases may use different symbols.

Phrase searching examples:

"White blood cells"

"evidence based practice"

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