Search Techniques: Building your search

The term 'Boolean' comes from the name of its originator George Boole (1815-1864). He developed a system of logic that now underpins the workings of modern computers. Boolean logic enables you to retrieve information from computers by expressing the relationships between words and phrases using language. Boolean Logic has three components AND, OR and NOT:

Boolean AND AND links concepts together. A database searches for results that contain Concept 1 and Concept 2, then compares the results to display only those results that contain both concepts. This can be represented using the Venn diagram right. The area in the centre where the circles cross represents the results that contain both terms/keywords.
Boolean OR OR combines concepts together. The database locates all the results that contain concept 1 and all the results that contain concept 2 then combines both groups of results into a single set. Each circle represents the results that contain the words humour and the results that contain the word comedy. Using OR retrieves all the results and these are represented by the total area of both circles.
Boolean NOT NOT excludes results that contain concepts that you do not want to find. Searching for advertising NOT marketing retrieves all the results that contain the word advertising, but excludes the results that contain the word marketing even if the word advertising is present. Each circle represents the results that contain the words advertising and the results that contain the word marketing. Using NOT only displays results containing the word advertising represented by half-moon shape of the advertising circle.

Quick 2 min video explaining Boolean (contact your Faculty Library Team if you seek further advice):

• Once you understand how Boolean operators work you need to go one step further and understand what happens when you combine more than one Boolean operator in the same search.
• Computers process the AND operator first and then the OR operator:
• Some search interfaces have Boolean built into the set up of their search boxes (e.g. BU Library's specialist academic database called EbscoHost provides an advanced search feature with multiple search boxes to combine search terms/keywords and Boolean drop-down menu selections).
• Or, if you are just using one search box in a specialist academic database, this technique can be applied:
  • If you enter: Homeless AND Teenage OR Adolescent
  • It will do this: Homeless AND Teenage OR Adolescent
  • Instead, you need to enter: Homeless AND (Teenage OR Adolescent)
  • Group the OR concepts together using brackets to surround those search terms/keywords ( ) and ensure the search is processed in the expected way.
• Search interfaces are usually designed to help you create logical searches that work.

Many terms in English have more than one ending depending on the context. When searching databases only the words you type in are retrieved. A complete search requires all the words with all possible endings to be included.

Truncation broadens the search to include various word endings and spelling, achieve this by truncating the word using an asterisk:

• Advert* = will find advert, advertising, adverts, advertisement, advertisements, advertisers, advertise
• Child* = will find child, children, childhood
• Learn* = will find learn, learning, learned, learnt
• Comput* to find the words computer, computers, computing and computation.

However, beware of going too far and over-truncating:

Diet* - will find diet, diets, dietary, dieted, BUT it will also find diethyl

Some search terms/keywords are better expressed as phrases or strings of keywords together to improve the precision of your search. Placing the phrase inside inverted commas means you will search for the entire phrase, not just its component parts.

Using double quotation marks searches for words in the exact order in any field in the metadata and full text (when applicable). Only use this technique to find multiple words in a particular order.
For example: 

• "social media"
• "global warming"
• "corporate social responsibility"
• “accident and emergency”
• “therapy dog” (note: entering that won’t find 'dogs for therapy', or 'dogs used in therapy', so consider also trying the Proximity searching technique)

This is a way to search for two or more words that occur within a certain number of words from each other.

The proximity near operator can be 'N' then include a number afterwards to indicate within how many words you like the next keyword you enter to be identified. Using the near operator in this way works in Ebscohost, how to input it can vary, depending on which database you use, check the database help section.

• e.g. using 'N3' finds the words if they are a maximum of three words apart from one another, regardless of the order in which they appear, so entering 'therapy N3 dog' would identify if an author has written 'dog used in therapy', 'therapy support dog' in their research.
• e.g. N5 finds the words if they are a maximum of five words apart from one another, regardless of the order in which they appear, so entering 'tax N5 reform OR tariff N5 reform' would match to find results that include 'tax reform' as well as 'tax that has been submitted for reform'.

Some terms present problems because letters within them change depending on the context e.g. UK and US spelling differences or plurals.

An asterisk / hash / question mark can sometimes be added somewhere to the search term / keyword.

For example:

• wom?n will find woman or women.
• colo#r will find both American and English spellings color and colour, as well as the singular and the plural of the word.

Check specific database Help sections to find which wildcard options to use: an asterisk / hash / question mark.