Transcript Document

Searching Skills Guide
Boolean, Truncation and Wildcards
Presented by: National Police Library
Date: June 2013
Why You Need This Guide
• This searching guide is for people who would like to
achieve better results when searching library catalogues
and academic databases.
• Why might you need this guide?
• You are struggling to find articles and resources on a topic
you are interested in.
• You want to ascertain whether any academic research on
your topic even exists!
• You are overwhelmed by the amount of literature out there
and want to reduce the number of results you are getting
but…
• …you want to make sure the results you do get back are
relevant and of high quality.
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The Basics
The purpose of Boolean logic
• Most, if not all, library catalogues and subscription
academic databases will enable the use of Boolean logic for
searching.
• Boolean (named for its inventor George Boole, a 19th
century logician and mathematician) is a system which
enables researchers to specify to a database which
keywords they want found, and what relationship these
words should have to each other. For example:
• Words like RESEARCH, STUDY and INVESTIGATE can all
mean the same thing. You want to find at least one but not
necessarily all of these words.
• You want to find literature on RAPE but not OILSEED RAPE.
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Boolean operators
• Boolean is a powerful tool and can be used to create
quite complex searches. The standard Boolean operators
are:
AND
OR
NOT (or AND NOT)
Boolean is most effective when used in combination with
parentheses (round brackets), truncation and wildcards.
These will all be explained in this guide.
•
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Example search strings
•
From the very simple:
crime AND punishment
good NOT evil
murder OR homicide
•
To the very complicated:
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Operators
Boolean ‘AND’
• When using AND in a simple search, the results
retrieved will contain both search terms. In the diagram
the documents retrieved by using this search expression
are contained within the green area.
EXAMPLE: violence AND crime
This will retrieve all records containing both of the words
violence and crime.
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Boolean ‘OR’
• OR is used to retrieve results that contain either search
term as well as to retrieve results that contain both search
terms. In the diagram the documents retrieved by
using this search expression
are contained within all
the colour areas.
EXAMPLE: violence OR murder
This will retrieve all records containing the words violence
or murder, as well as those containing both.
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Boolean ‘NOT’
• When using NOT (or AND NOT) in a simple search, the
results retrieved will contain only the term used before the
NOT. In the diagram the documents retrieved by using
this search expression are contained within the light blue
area.
CRIME
MURDER
EXAMPLE: crime NOT murder
This will retrieve all records containing the word crime but
not the word murder.
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Use of ‘NOT’
• The NOT operator can hinder your search if used without
care. While it is fairly certain that a search for:
rape NOT oilseed
…would not inadvertently exclude results relevant to you,
the same cannot be said for:
murder NOT accident
• While seemingly distinctive topics, this search would
exclude ‘Murder is no Accident’ from the results.
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In the Catalogue
Simple Boolean searches
• You can use Boolean to perform simple searches in the
National Police Library Catalogue* in two ways. From the
advanced search screen you can:
1. Use the ‘drop down’ to
combine search terms.
2. Write Boolean operators
between words in a search
box.
*The library catalogue Heritage is a product of IS Oxford Ltd. The National Police Library online catalogue can be found
at http://library.college.police.uk/default.htm
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Layered Boolean searches
• With only what we’ve learned so far, we can also create
slightly more complicated searches:
• In the search shown above the documents retrieved
would contain the word murder, either or both of the
words police or policing, and would not contain the word
serial.
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Search Logic
Order of Operations 1
• In simple searches, Heritage and many other search
engines will process search terms from left to right.
• This helps the system recognise phrases and titles,
therefore producing more relevant results*.
• However, as in maths, there is an Order of Operations for
using Boolean operators.
• AND will be processed before OR.
• AND NOT will be processed before AND.
*For information on exact phrase and title searching using quotation marks, see slide 21.
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Order of Operations 2
• Consequently the way in which a search is constructed
can have big implications for the search results. Lets say
we want to find results related to corruption in the police.
Search for…
… and you will get
• Because the search combines policing and corruption,
and then retrieves all catalogue entries containing the
word police as well!
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Adding Structure
Parentheses or round brackets
• The simplest way to get the results you require is to
group synonyms (or terms that belong together) using
round brackets. Anything enclosed in brackets will then be
worked out first.
Using the example from the previous slide, we can see
that using brackets ensures we get the correct search
results.
•
Search for…
… and you will get
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Advanced search
• Making good use of the advanced search functions can
also help reduce search errors. This is because the search
boxes provide structure for the system to follow.
• All three searches above will produce the same results in
the library catalogue.
• Advanced search functions can be combined with the use
of brackets for very complex searches.
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Inclusive Searching
Word form variants
• We are used to search engines which will try to interpret
what we ‘meant’ to search for. However most databases
and catalogues require precise spelling and word form use.
• In searching therefore, it is important to account for all
applicable word forms.
• One way to do this would be to literally search for all
tenses and forms of a word or phrase:
• Police: police OR policing OR policed...
• Rape: rape OR raping OR rapist OR raped…
• Sex offender: sex offender OR sex offence OR sexual
offence OR sexual offending OR…
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Truncation
• The easiest way to account for all variant word endings is
to use to technique known as truncation.
• Truncation is used by databases in order to expand a
search to include all word endings and minimise the need
to enter (or remember!) multiple word forms. The stem of
the word is entered into the search box followed by the
truncation symbol, often *.
• Politic* retrieves political, politics, politically.
• This technique cannot be used with all words though.
• Polic* retrieve police, policing, but also policy
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Wildcards
• You can account for alternative spellings of a word by
using wildcards. Wildcard characters are used to replace a
single letter in a word, like the blank tile in Scrabble. A
commonly used wildcard symbol is ?.
• Organi?ation retrieves organisation, organization.
• Breathaly?e retrieves breathalyse, breathalyze.
• Many databases will also use multi-character wildcards.
These can be used to replace 1, multiple or 0 characters
within a word, depending on the database. Symbols used
include #* and $.
• H#emorrhage retrieves Haemorrhage, Hemorrhage.
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Combining symbols and database variation
• Most library databases use truncation and wildcards, and
the two can be combined if required. It is advisable to do
this with caution however, especially when using multicharacter wildcards.
• Colo#r* retrieves Colour, Color, Colouring,
but also might retrieve Collateral, Collars etc.
• When using truncation and wildcards it is important to
be clear on what symbols a database uses and what rules
apply to their usage.
• The table on the next slide shows the different symbols
used by some of the main databases that the National
Police Library provides access to.
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Database specific symbols
Database
Truncation
symbol
Wildcard
symbol
Multi-Character Wildcard symbol(s) and
usage notes
Heritage
*
?
* Finds any number of unknown characters
EBSCO
*
?
* Finds any number of unknown characters
# Finds 0 or 1 unknown characters
ProQuest
*
?
* Finds up to 10 unknown characters
[*n] Finds up to N unknown characters
Westlaw
!
*
Not available
Emerald
*
?
* Finds any number of unknown characters
Web of
Knowledge
*
?
* Finds any number of unknown characters
$ Finds 0 or 1 unknown characters
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Other Tips…
Double quote marks
• To search for an exact phrase, for example Police and
Crime Commissoners use double quote marks “”. In most
databases (including Heritage) you can use this function in
conjunction with truncation or wildcards.
• Double quote marks can also be used where Boolean
operators appear in a title to override the systems desire
to AND, OR or NOT.
• “Police and crime commissioner*”
• “Naked and Not Ashamed” (genuine book title)
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Keywords and subject terms
• Keywords or subject terms used by databases can be
useful for creating a specific search, but should be used
with caution as they vary wildly across, and even within
databases.
• A general search for cyber-crime finds a variety of
keywords across databases:
• If you wish to make use of a database’s keywords or
subject terms it is recommended that you investigate the
terms used in each database thoroughly.
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Proximity operators
• In addition to Boolean, wildcards and truncation, many
databases include additional proximity operators to help
you with your search. The most common are:
• NEAR – used to define how close together you would like
terms to appear in a search.
• WITHIN – used to define how close together you would
like terms to appear and in what order
EXAMPLES:
In the table
Shown, #
represents a
number
Database
NEAR
WITHIN
EBSCO
N#
W#
ProQuest
NEAR/#
PRE/#
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Using Search Engines
• Search engines tend to have their own search functions
which are loosely based on Boolean principles. However, as
they provide access to such vast reams of information,
searching them successfully can prove tricky.
• While this guide is not designed to assist with using
search engines, some tips on searching Google are
included here to help you make the most of this resource:
• The minus symbol ‘-’ is used for NOT.
• The plus symbol '+' can be used for AND, although Google
will AND words by default
• Double quotes “” are used for phrase searching.
• For more information, read Get more out of Google
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Contact Details
National Police Library
• For further information, or assistance with searching and
information retrieval, please contact the National Police
Library at:
•
National Police Library
College of Policing
Albert Day Building
Sunningdale Park
Larch Avenue
Ascot
Berkshire
SL5 0QE
•
•
T 01256 602650
E [email protected]
All rights reserved, no part of this publication may be reproduced, modified, amended, stored in
an retrieval system or transmitted, in any form or by any means, without the prior written
permission of the National Police Library.
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References
• ADAM Consortium. Boolean searching. ADAM Consortium: Surrey. [Accessed 24 April 2013]
http://adam.ac.uk/info/boolean.html
• CATONE, J., 2011. How to Use Google Search More Effectively [INFOGRAPHIC]. Mashable.
[Accessed 24 June 2013] http://mashable.com/2011/11/24/google-search-infographic/
• EBSCO, 2013. EBSCO help: basic search. EBSCO. [Accessed 24 April 2012]
http://support.ebsco.com/help/index.php?help_id=50
• Emerald, 2013. Detailed “advanced search” functionality. Emerald Group. [Accessed 10 May
2013] http://www.emeraldinsight.com/help/user/advanced_functionality.htm
• IS Oxford, 2013. Heritage: library management software. IS Oxford: Oxford. [Accessed 11 July
2012] http://www.isoxford.com/
• JAKES, T.D., 2005. Naked and not ashamed. Destiny Image: Shippensburg, PA.
• Proquest, 2013. ProQuest help: basic search. Proquest LLC. [Accessed 24 April 2013]
http://search.proquest.com/help/academic/webframe.html?Basic_Search.html
• PROTHROW-STITH, Deborah; SPIVAK, Howard R., 2004. Murder is no accident: understanding
and preventing youth violence in America. San Francisco: Jossey-Bass.
• University Libraries, 2010. Using AND, OR, and NOT (Boolean Operators). University of Nevada:
Reno. [Accessed 11 July 2012]
http://knowledgecenter.unr.edu/help/using/booltips.aspx#parenthess
• User Education Services, 2012. Using Boolean Logic or Connectors. University of Maryland
Libraries: Maryland. [Accessed 10 May 2013] http://www.lib.umd.edu/ues/guides/boolean-logic
• Westlaw, 2013. Westlaw UK Help - Terms and connectors used on Westlaw UK. Thomson Reuter.
[Accesses 23 April 2013] http://login.westlaw.co.uk/
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