Lecture 4 Access Tools/Searching Tools

Learning Objectives To define access tools To identify various access tools To be able to formulate a search strategy To retrieve accurate and relevant information based on the access tools

1.How can i search for information on the internet 2.How do I search for books in the UZ library

Access tools- these are information finding aids Access tools are utilities used to locate information, such as ◦ Library Catalogue (OPAC) Internet Search Engines ◦ Internet Search Engines ◦ Subject gateways/portals ◦ Databases ◦ Bibliographies Different access tools are used to find different kinds of information

Library Websites

OPAC

Advantages of using OPAC it is specific i.e. shows the actual location of the item it shows the status of the book (is it available or not) it is fast and efficient it enables you to carry out simultaneous searches no geographical boundaries (remote access) It enables you to limit your search to a particular section of the library

Search Engines

What is a web search engine?

A web search engine is designed to search for information on the World Wide Web. The search results are generally presented in a list of results often referred to as search engine results pages (SERPs) or hits.World Wide Websearch engine results pages The information may consist of web pages, images, videos, sound and other types of files.web pages

How does a search engine works A search engine operates in the following order: Web crawling Indexing Searching

Web search engines work by storing information about many web pages, which they retrieve from the internet. These pages are retrieved by a Web crawler (sometimes also known as a spider) — an automated Web browser which follows every link on the site.Web crawler The contents of each page are then analyzed to determine how it should be indexed (for example, words can be extracted from the titles, page content, and headings).indexed Data about web pages are stored in an index database for use in later queries. The purpose of an index is to allow information to be found as quickly as possible. When a user enters a query into a search engine (typically by using keywords), the engine examines its index and provides a listing of best-matching web pages according to its criteria, usually with a short summary containing the document's title and sometimes parts of the text.querykeywordsindex

Popular Known Search Engines Google ( Altavista ( Yahoo ( Ask ( MSN Search ( ) Exalead ( ) Gigablast (

Types of Search Engines General Search engines Meta search engines Directories Specialized/Vertical Search Engines

General Search Engines A general search engine is a search engine that covers the overall Web, using its own spider to collect Web pages for its own index.

When to use general search engines? When one has a well-defined topic or idea to research When one’s topic is obscure When one is looking for a specific site When one wants to search the full text of millions of Web pages When one wants to retrieve a large number of Web sites on one’s topic When one wants to search for particular types of documents, sites, file types, languages, date last modified, geographical location, etc.

Examples of general search engines General search engines have been popular and newsworthy for many years. Google ( ) Bing ( ) Bingwww.bing.com Yahoo! ( ) Yahoo! Gigablast ( Exalead (

Meta search engines A meta-search engine is a search tool that sends user requests to several other search engines and/or databases and aggregates the results into a single list or displays them according to their source. Metasearch engines enable users to enter search criteria once and access several search engines simultaneously.

Meta search engines operate on the premise that the Web is too large for any one search engine to index it all and that more comprehensive search results can be obtained by combining the results from several search engines. Results retrieved by these engines can be highly relevant, since they are usually grabbing the first items from the relevancy-ranked list of results returned by the individual search engines. Keep in mind that complex searches, such as field searches, are usually not available. This also may save the user from having to use multiple search engines separately

When to use meta search engines? When one wants to retrieve a relatively small number of relevant results When one’s topic is obscure When one is not having luck finding what you want When one wants the convenience of searching a variety of different content sources from one search page

Examples of meta search engines DogPile ( Metacrawler ( Search.com ( ) Clusty ( ) Mamma ( )

Directories These are manually created by people that do a lot of surfing on the Internet, picking up and evaluating the content of a web site and if the content fits into their selection criteria, it is put in the directory. It is the same way you compile a telephone directory. Directories use subject headings to categorize their information, e.g. business management could be a heading. Examples of web directories are Lycos and Yahoo. Directories usually have very little content, they may contain links (pointers) to sites that have got the information you are looking for.

Specialized/Vertical Search Engines A specialist searches a specific subject, industry, topic, type of content (e.g., travel, movies, images, blogs, and live events), piece of data, geographical location, and so on. It may help to think of vertical search as a search for a particular niche. Some of this content cannot be found, or is difficult to find, on general search engines. To find a vertical/specialist search engine, one can use a general search engine and try to find a search site dedicated to a particular type of content, for example medical search, job search, and so on.

When to use specialized search engines? When one’s topic is focused on a specific topic, industry, content type, geographical location, language, etc. When one is having difficulty locating what they want on general, meta, or concept categorizing search engines

Health Sciences PubMed ( Sciences World Wide Science ( ) World Wide Sciencehttp://worldwidescience.org Full Text Scholarly articles Google Scholar Images search Picsearch ( ) News search engines Newslookup.com ( Social networking FriendFeed Search( )

Advantages Best Suited for complex keyword/concept searches Currency of information made possible by regular addition Searches can be limited to a period of time, fields, source type, etc Currency of information, made possible by regular addition by web spiders Exhaustive information can be retrieved (with a lot of patience )

Disadvantages of using search engines False positives Dead links/ redundant links Spamming Search engines vary in terms of searching techniques Higher ranking of paying sites