Information and Communication Technology

Search Techniques

Using appropriate search techniques and queries to locate and select relevant information

For many people, searching on-line means 'put a word into a search engine and see what comes up'.

This search technique will usually find some relevant information, but it will often find a huge amount of other stuff as well.

This page looks at how to improve your search technique in order to produce fewer, but more useful results.

NOTE. The graphic shows Trademarks and Logos to illustrate the concept of search engines. These are not Public Domain images.

Search Criteria

Search criteria are essentially the keywords that are used by a search engine, or similar piece of software such as a database query or a word processor find tool, to filter out matching results.

Search criteria need to be selected with care in order to optimise the results that are returned.

A single keyword may produce a huge number of results which contain that keyword, but most of them will have little or nothing to do with the information being sought.

Using too many keywords may produce a small number of useful results, while excluding many more which would have been useful but didn't have all the required words.

Operators

An operator is a means of constructing relationships among search terms. There are several different kinds of operator and different search engines or search tools allow different sets of operators to be used.

Some of the most common are:

Relational.

= equals, > greater than >= greater than or equal to, < less than, <= less than or equal to.

This type of operator is used most frequently when searching data sets. e.g. in a database, but it could be used in a search engine, e.g. when looking for something that happened between two dates.


Logical. AND, OR, NOT. These are used to link two or more criteria. e.g. if the criteria are History and Laptop:


Logical operators can be combined, but care must be taken with the order.

e.g. Laptop AND History AND Computer, would need all three words in the result as expected.

BUT.. Laptop OR Computer AND History, would give results for Laptop History OR Computer History,

While... Laptop AND Computer OR History, would give results for Laptop Computer OR History

The order in which the criteria are processed may be forced by using brackets.

e.g. Laptop OR (Computer AND History) would give Laptop or Computer History.

For most search engines, AND is assumed as default. So Laptop History would be processed as Laptop AND History.


For most other search tools, e.g. one in a database, the operator must be put in.

Some search tools also allow other logical operators, common ones being:

Wildcards

A wildcard is a character that may be used in place of another character or group of characters in search criteria.


The common ones for search engines are ? and * but other search tools may allow different ones such as [ ], { }, ^ and -.


? means that any single character may appear instead of the ?

e.g. co?e will return results for code, coke, cole, come, cone, cope, core, cote and cove.

* means that any number, including zero, of characters may appear instead of the *

e.g. storm* will return results for storm, stormed, storming, stormier, and storms.

[ ] means that any of the characters inside the brackets may be used.

e.g. c[aou]t will return results for cat, cot and cut.

^ means that any character that is not in the brackets may be used.

e.g. c[^u]t will return results for cat and cot but not cut.

- means that a range of characters can be used.

e.g. co[l-r]e will return results for cole, come, cone, cope, and core, but not code, coke cote and cove.

{ } means that any of the groups of characters inside the brackets may be used.

e.g. c{a, as, lou, u}t  will return results for cat, cast, clout and cut.

Other search techniques

Apart from the ones given above

There are many other search techniques available to help find information, some are common to a lot of software types, most are limited to a particular package, subject or type of search.

Some of the common ones are:

Using quotation marks " " to surround a phrase (set of words), will return results with that phrase.

Using a wizard, if the search engine or software has one, will allow complex searches with use of several operators and wildcards without having to get the exact order and punctuation correct.

Where a wizard is not available, searching within search results can also reduce the requirement for getting a complex search laid out correctly. e.g. searching for laptops, then searching within those results for history and then for 1990.

Specifying file types as one of the search criteria can be useful when looking for e.g. a piece of music (mp3 or wma) rather than text about the piece of music.

Using specialist search engines. e.g. Google Scholar, for academic papers, journals and similar types of sources.

Or Wolfram Alpha, which tries to calculate answers to factual questions by using a knowledge base of structured data.

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