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Medical Sciences: Search skills for systematic reviews: Creating an effective search

This tutorial will guide you through the steps required to systematically search for your research projects.

Search words picture

Can a librarian devise my search strategy for me?

No - this is not permitted. 

The Library does offer support on:

  • where to search,
  • using databases,
  • search techniques, and
  • saving and exporting search results.

These books offer practical guidance on every step of the systematic review process.

How should I search for literature in a database?

Creating an effective search strategy is critical to undertaking a comprehensive search and identifying all relevant studies for your research question. After breaking your research question into discrete concepts, expanding those concepts to identify additional keywords and considering the search techniques you should use (such as truncation, wildcards, phrase or proximity searching), you will need to use the boolean operators (AND, OR, NOT) to combine the concepts into a search strategy for use in the databases. Search techniques do vary between databases use the help section to find out the ones in use in your chosen database. 

You can test a search by checking whether known articles are appearing in the results list. If they aren't, this is a clue that you may need to revise your search and possibly add additional terms.

2. Combining your search terms

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.

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: caffeine AND performance
will only return results where both words are present

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: adolescent OR teenager
                      - will return results where either one or both of these words are present

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.

Use NOT to narrow your search.

Using NOT narrows your search as it instructs the database to ignore results that contain particular words.

For example: social media NOT twitter
- will return results that include social media but do not  include twitter

NOT  tends to be used less than the And and OR operators. 

Use it with care as you may exclude useful articles which cover a range of topics of relevance to you.

3. Using search techniques to improve your search

Truncation is a technique that broadens your search to include various word endings and spellings.

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.

The asterisk * symbol is most commonly used for truncation. However, check out the help screens as  !, ?, or # may also be used.

For example:

child* will find child, childrenchildlikechildhood etc.

diet* will find diet, diets, dietary etc.

method* will find method, methods, methodology 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 screens 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:

"Cognitive Behavioral Therapy"

"pain tolerance"

Proximity searching can help to both increase or narrow your results. It can increase your results when "phrase searching" is too restrictive.

Using an operator such as ADJ or NEAR  to define the proximity between your keywords can be helpful in increasing the precision of your results compared with using AND to combine the keywords 

e.g. mindfulness ADJ3 treatment returns results with the keywords "mindfulness" and "treatment" within three words of each other in either direction. 

Tip - check the help section of the database you are using as these operators differ across different databases.

Proximity searching should be used with caution in systematic reviews to avoid losing relevant studies.

Records in databases are made up of fields containing pieces of bibliographic information which describe the item in details.

Fields differ between databases but common fields include:

  • author
  • title
  • journal title
  • abstract
  • publisher
  • date / year of publication
  • subject / descriptor

If you are overwhelmed by search results, then using field searching can make your search more focused as databases usually run a keyword search against the full database record leading to a wider search.

What is a search string / search strategy?

search string or strategy is a combination of keywords, truncation symbols, and boolean operators you enter into the search box of a database. Here are some examples: 

Caffeine AND (dose OR dosage OR exposure) AND performance

(pain* OR discomfort OR “chronic pain”) AND (mindful* OR MBCT) AND (depress* OR anxi*)

OR is used to find the alternative words used to describe a concept or idea. 

Brackets are used to group the OR words together so they are processed together. 

AND is used to link the search concepts together and find material that contains all aspects of your question.

If you are entering your search in one search box it is important that you use AND, OR and Brackets in combination so that the search is processed correctly. 

Alternatively, use the Advanced Search option to separate out your search terms (entering each concepts keywords in a separate search box), this saves you having to add the parentheses.  

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