Search strategies

A search strategy is a systematic plan for conducting a search. This plan comprises four steps:

  1. Understand your topic and define your search terms
  2. Create your search strategy
  3. Select an appropriate tool
  4. Evaluate your resources

Search syntax for developing search statements

Subject, keyword and author searching allow you to create effective searches. To search more efficiently, combine terms in a logical way using Boolean and/or proximity operators, truncation and parentheses.

Boolean operators

Boolean operators form the basis of database logic. They connect your search words together to either narrow or broaden your search. Let's consider AND, OR, NOT.

The 'AND' operator

Use AND to connect different concepts. Using AND directs the database to show records that include all the search terms that were used in the search. All search terms will be listed in the results. The more search terms connected by AND, the more specific your search will be and fewer records will be retrieved. Be aware in some databases AND is implied.

The 'OR' operator

Using OR broadens the search to include all records that contain any terms used in the search. This type of search links like terms or synonyms together. Each time you add another term with the OR operator you are potentially increasing the number of records that will be retrieved. You can use OR to search for synonyms, alternate spellings, or abbreviations.

The 'NOT' operator

Use the NOT operator to exclude certain words from your search. Using NOT narrows the search by excluding specific terms. Be aware that this is a powerful search operator and may also exclude important records.

Watch the video to check your understanding of: Boolean operators (YouTube video, 1m48s)

Phrase searching

Some databases assume that a string of words will be searched as a phrase whereas others will search on each individual word. Phrase searching tells the database to look for two or more words in the exact order they are entered. Use the quotation marks "" to enclose a phrase.

Example: Searching for "climate change" finds this exact phrase, excluding irrelevant results about 'change'.

Watch the video: Phrase searching (YouTube video, 38s)

Proximity operators

Proximity or adjacency operators allow you to locate one word within a determined distance from another. Words that are close to each other are more likely to be related than those that are further apart. Using proximity operators will limit your search returning a smaller, group of results. Proximity operators differ between databases. Check the database help screens to find out which operators are appropriate to the database you are using.

Watch the video: Proximity searching (YouTube video, 1m38s)

Truncation and wildcards

Use truncation symbols to look for the root or stem of a word. The most commonly used truncation symbol is the asterisk *.

Example: The search creat* will retrieve create, creates, creator, creative, creativity etc.

Be careful to use a word stem that relates to your meaning.

Example: The search polic* will return policy and policies, as well as police and policing.

A wildcard symbol is used to substitute for a character either within a word or at the end of a word. This symbol is particularly useful for American or British variations or when you're unsure about the spelling of the word.

Example: The term organi?ation will find both 's' or 'z' spellings.

Truncation and wildcard symbols vary between databases and internet tools, so check the help section of each database.

Watch the video: Wildcards and truncation (YouTube video, 426s)

Nesting terms

Nesting search terms within parentheses () controls the logic of the search so you can group synonyms in sets. The part of the search within the parentheses is performed first.

Example: The search ("respiratory tract infection" or bronchiolitis) and management finds articles about the management of either respiratory tract infections or bronchiolitis.


You may also use limiters to narrow your search. This is often best done in the results screen to increase the relevancy of results after a comprehensive search. Limiters include:

  • subject
  • format
  • date
  • institutional affiliation
  • full text or peer reviewed articles.

Search engines such as Google have their own limiters including:

  • domain - restrict to a country, type of organisation or information provider (.au, .edu or .gov for Australian, educational or government information)
  • format or file type - such as PDF, PPT, Excel, audio or video files to focus your search
  • region
  • last updated.

Deciding how to search

Keyword searching

Most databases search keywords or words anywhere unless you choose another type of search. The database looks for a match for your keyword in any field in the record. This means that your search will retrieve more information or have higher recall but be less precise than other searches.

Watch the video: Keyword searching (YouTube video, 1m28s)

Field searching

Some databases allow searching in specific fields such as the title, author, or subject. This type of searching is quite specific and will retrieve fewer results than a keyword search. By using field searching you can increase the precision of the search thereby retrieving fewer results.

Example: Searching for bank in the author field retrieves results by authors called 'Bank', while searching for bank in the keyword field might retrieve results about financial institutions or rivers.

Example: Searching for constructivism in the article title field is a quick way of finding articles about that theory, rather than articles that merely mention it in passing.

Subject searching

Subject searching can increase the relevance of your results. Each database record lists subject terms. Also known as subject headings, descriptors or index terms, these are a set of standard terms or controlled vocabulary that are defined and used by indexers of the database to describe a subject so it can be easily found. There are many terms that mean the same thing, using subject headings aims to bring these like terms together under a single term or phrase.

Watch the video: Subject searching (YouTube video, 2m16s)

See Table 1 for an example of the development of a database search query string used in a nutrition science research question to investigate if dairy proteins help to suppress a feeling of hunger.

Note the various types of searches - keyword and the use of search techniques, including phrase searching, proximity searching, truncation, nesting, AND/OR/NOT, subject heading searches (indicated by MH for medical subject headings), limiters to publication type and the combining of sets (e.g. S8 or S9), which can be accessed from the search history in the databases.

Table 1: Search strategy
Search Query Limiters/Expanders Last Run Via
S23 S18 AND S21 Limiters - Date of Publication: 19700101-20141031; English Language; Human MEDLINE
S22 S18 AND S21 Search modes - Boolean/Phrase MEDLINE
S21 S19 OR S20 Search modes - Boolean/Phrase MEDLINE
S20 (PT "Randomized Controlled Trial") OR (TI "randomi?ed controlled trial#") OR (AB "randomi?ed controlled trial#") Search modes - Boolean/Phrase MEDLINE
S19 (PT "Clinical Trial") Search modes - Boolean/Phrase MEDLINE
S18 S16 AND S17 Search modes - Boolean/Phrase MEDLINE
S17 (MH "Adult") OR (MH "Middle Aged") Search modes - Boolean/Phrase MEDLINE
S16 S7 AND S15 Search modes - Boolean/Phrase MEDLINE
S15 S10 NOT S14 Search modes - Boolean/Phrase MEDLINE
S14 S11 OR S12 OR S13 Search modes - Boolean/Phrase MEDLINE
S13 (MH "Milk, Human") OR milk N2 human Search modes - Boolean/Phrase MEDLINE
S12 (MH "Infant Formula") OR infant N2 formula* Search modes - Boolean/Phrase MEDLINE
S11 (MH "Margarine") OR margarine Search modes - Boolean/Phrase MEDLINE
S10 S8 OR S9 Search modes - Boolean/Phrase MEDLINE
S9 dairy AND ( bioactive OR bio-active OR calcium ) Search modes - Boolean/Phrase MEDLINE
S8 (MH "Dairy Products+") OR dairy N2 product# Search modes - Boolean/Phrase MEDLINE
S7 S1 OR S2 OR S3 OR S4 OR S5 OR S6 Search modes - Boolean/Phrase MEDLINE
S6 (MH "Energy Intake+") OR "energy intake" Search modes - Boolean/Phrase MEDLINE
S5 calor* N2 intake Search modes - Boolean/Phrase MEDLINE
S4 (MH "Hunger+") OR hunger Search modes - Boolean/Phrase MEDLINE
S3 fullness Search modes - Boolean/Phrase MEDLINE
S2 (MH "Eating+") OR (food N2 intake) Search modes - Boolean/Phrase MEDLINE
S1 (MH "Satiation+") OR sati?t* Search modes - Boolean/Phrase MEDLINE

Step your searches

Searching is the process of finding out what is available via a search tool, changing and developing your search statements accordingly, and limiting the view to construct the best set of results possible. A database has different screens specialising in advanced search, refining results and working with results. Think about how you will search. What will be your search process? This step by step approach may be useful in determining your method.

  1. Determine search objective - identify initial key concepts, synonyms and alternative term.
  2. Conduct a preliminary keyword search - evaluate results for the most suitable records and glean suitable alternative terms.
  3. Comprehensive keyword search - broaden your search with alternative terms for comprehensive results.
  4. Subject and keyword search - scan for subject terms, use the drop-down indexes.
  5. Apply limiters to results to increase relevancy (e.g. subject, date, format).
  6. Export citations and download files.

Activity 1 – Watch these videos

Watch these videos for an example of how to map the research question and an overview of search strategies.

Watch the video: Planning your search and the OR operator (YouTube video, 5m04s)

Watch the video: Phrase searching, wildcards, truncation (YouTube video, 5m06s)

Watch the video: AND operator, nested searching, proximity searching (YouTube video, 6m30s)

Watch the video: What is a subject heading? (YouTube video, 5m12s)

Activity 2 – Map the search process

Using your research question map the search process for your research topic in your Resource Log. It will be a record of the terms, synonyms and strategies you have used to collect information, as well as the tools you have consulted. Consider the strengths and limitations of each database.