Resource Characteristics

The characteristics of individual resources have an affect on searching and information retrieval. What follows is a brief overview of various resources.

Online Databases vs. Search Engines vs. Web Directories

Online databases, search engines, and Web directories are entirely different electronic beasts. Each has unique characteristics that affect searching behavior.

Online Database

In very simplistic terms, an online database is a collection of records containing information organized by fields. In the library world, we are most familiar with databases containing records of information related to articles found in journals, magazines, and newspapers, among other sources. The database is usually produced by a commercial entity that may or may not be the originator of the information itself. Information included in the database is selected by the producer, is usually drawn from print sources, and is presented to the end user through a Web-based interface. Most online databases in the library world are available by subscription as opposed to freely available via a network connection.

Search Engines

A software program that allows end users to search data. While the phrase is used to generally describe that software and its capabilities, we more commonly think of search engines provided by specific entities -- Google, AltaVista, Teoma. The data being searched in this case is information related to Web sites. As we'll lean in the section on Search Engines, this information is gathered (indexed) using specialized programs called spiders or robots. Their purpose is to gather words from Web pages and put them into a searchable index. This gathering is highly automated with spiders sent to crawl Web pages nearly all hours of the day.

Web Directory

A Web directory provides access to Web sites in a more organized fashion. Usually, Web directories are created by companies in which Web sites are submitted for inclusion as determined by human reviewers. Most are organized according to subject or topic. Many include a search engine capability, where end users can search for information from within the directories (as opposed to the entire World Wide Web).

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Selecting the Appropriate Resource

Depending upon the end user's need, selecting the appropriate resource will have an affect on the search outcome. Some characteristics of online databases, search engines, and Web directories that should be considered when planning a search include:

Is the database considered:
»full-text : contains the full text of the article
»citation : contains only bibliographic citation information such as author, title, journal name, and an abstract
»statistical data : contains only numeric data, such as Census files

»Date Ranges : what is the date range of materials covered by the database, search engine, or Web site? Depending upon information need, an end user may need a resource that covers more historical information (usually older than 15 years)
»Subject Area/Literature coverage : is the resource devoted to individual subject areas, broad topic coverage or selective in its coverage of fields of literature?
»Currency of the Database : it may be important to know how often the resource gets updated. This is particularly true in competitive arenas such as patents, engineering, and medicine.

»availability : free vs. subscription?
»accessibility to information (entry points -- multi-field indexing) : are you able to search all fields in the database record? Those areas not indexed may be just as important as those that are.

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Other Evaluation Criteria

You may also want to consider the criteria outlined by the Southern California Online Users Group (SCOUG) in Reva Basch's article. The criteria are provided at http://www.bubl.ac.uk/archive/lis/org/ciqm/databa1.htm.

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