Web Searching, Sleuthing and Sifting
Power Search Techniques (Boolean and Field Searching)
This week we are going to explore Power Search Techniques. There are many excellent guides describing Boolean logic and charts showing the features available at the "major" search engines, which you should consult for more details (please see the section For More Information). Here, our purpose is a brief overview of possible techniques. Please note that while most of the major search engines we have been using allow some advanced search capabilities, they appear or are implemented differently.
And of course, we'll be going on another Info Quest.
Why "Power Search?"We've all had the experience where we query a search engine and come back with thousands, maybe hundreds of thousands of "hits" or "matches" for our search terms. Unfortunately, it is time-consuming to sift through the web sites, and usually not very profitable. When you obtain a large number of "hits" from a search, this is known as high recall. While this might be the goal in some cases (for example, if you are working on a topic that is relatively new and you want everything published on it -- and the number of "hits" is only a couple of hundred), for the most part when people are searching the web, they are interested in high precision. High precision means that the retrieved documents are highly relevant to your subject, and is achieved by fine tuning your search to accurately describe your topic with its unique aspects.
Many advanced web searching techniques are old friends of folks used to searching more traditional databases, such as those containing bibliographic citations or references to journal articles. Some techniques are unique to the web because of its media and structure.
Important Note: not all advanced
techniques are enabled by all search engines! Consult one or two of the
charts in For More Information and/or read the Help documentation of the
search facility you are using.
What is Boolean Searching?Boolean searching is an implementation of Boolean logic and set theory. Boolean operators, such as AND, OR and NOT, are used to combine search sets in a variety of ways and appear within Internet search engines in a range of disguises. A very brief overview:
means find web pages in which both terms occur
Search phrase: cats or dogs
means find web pages in which either term occurs
Search phrase: cats not dogs
means find web pages in which the term cat appears but not dog
Most web search engines have the capability to implement these basic Boolean operators but may present them in a different way. You will almost always need to go to an "Advanced" search function to use true Boolean operators; however, you may be able to search using implied Boolean using the symbols + (must include) or -(exclude) from the "Basic" search interface.
Examples of usage:
Special Note: these Boolean operators are often presented as options
like "include all the words," (AND operator) "include any of the
words," (OR operator) and "exclude" (NOT operator).
What are "Proximity Operators"?Also Boolean Operators, proximity operators such as NEAR or ADJ are used to control how closely the terms occur in the web document that is retrieved. For example, NEAR/3 means that the terms must occur within 3 words of each other. Proximity operators ensure that your terms are more closely related to another.
Examples of usage:
Special Note: the ADJ Boolean operator is often disguised as the option "exact phrase."
What is Field Searching?Remember that a web search engine is only as good as its database and indexes. Databases are collections of records organized in a similar manner; simply put, this means they are divided into fields that contain the same information in each record. If data is entered into a separate field you can retrieve it using its field label. This means that if you want to search by title, the search engine looks in a special title index (or searches notations that indicate that the term occurs in the title field) where it has collected data from the field with the label title.
Field searching is so wonderful because you can specify where to look in the web document; for example, in the title only, or the url fields. Field searching allows you to be very specific about where you want you terms to occur and hence is a very powerful tool.
Using Search templates:
I'm a big fan of advanced search templates such as the ones used by Hotbot (http://www.hotbot.com) and Snap (http://www.snap.com). These templates use many Boolean and field searching techniques without having to learn the syntax of yet another search engine.
For More Information, take another online course!Recommended:
Diane Kovacs, well known Internet Trainer and Writer, will be teaching a class in advanced searching techniques in the Spring. For more information and registration information, go to http://www.kovacs.com/online.html. The class, called "Finding Real Information on the Web: Advanced Web Searching Tips and Techniques," may also be taken any time in email format.
For More Information:
Excellent explanation of Boolean logic with diagrams.
Contains a chart describing an information need and which Internet search facility to use.
Brief, informative summaries of the features of the search facilities.
Contains general information on how to search; also information on selected search engines and a neat "practice" facility.
Series of 12 tutorials focusing on 48 topics containing lots of tips on "Power Searching."
Contains in-depth charts describing information needs and which search facilities to use.
A relatively recent article on field searching using the major search engines.
"NetLearn is a directory of resources for learning and teaching Internet skills, including resources for WWW, email and other formats. Links with descriptive and evaluative annotations are provided, covering: learning, teaching, navigating and providing information on the Internet; learning HTML; demographics; special needs and foreign language resources. " Well organized and comprehensive.
This table contains useful information about such as database sizes, Boolean and other search options and miscellaneous special features.
Includes a clear and concise description of advanced search techniques.
Includes a useful table comparing popular search engines' capabilities ("Cheat sheet") and a glossary of terms. Concise and to-the-point.
Assignments:Please use search engines only to find your answers so you can practice some of the advanced searching techniques.
1. Please answer the following questions with site address and actual answer.
Last updated: March 4, 1999 Links checked: March 4, 1999