Information Resources: Needle in a Haystack? Finding Health Information on the Web

Key Words: World Wide Web sites, health information, searching

How big is the haystack?

Finding information on the Web can be time-consuming and unpredictable. Web growth is a cycle fueled by more users, more sites, more Web pages. A recent article in JAMA reported that Internet users in 1998 were estimated at 80 million in North America alone, up from 3 million worldwide in 1994 (Coelho, 1998). This influx of users has been accompanied by tremendous growth in the number of individuals and organizations publishing and offering services online.

Network Wizards, in their 1999 Internet Domain Survey found over 43 million named, Internet host addresses (Network Wizards, 1999). Lawrence and Giles (1998) estimated that publicly indexable Web sites minimally contain 320 million pages. A 1999 report by the same authors put the number at 800 million pages (Lawrence & Giles, 1999). Of these, 83% are commercial and only 6% have scientific/educational content.So it is little wonder that health professionals and consumers can easily be swamped and find that the time spent searching for credible, current information on the Web is not used efficiently. In fact, Coelho (1998) cited classic informatics theory which "shows that as information increases, the amount of irrelevant and inaccurate information (often referred to as '˜noise') also increases."This column will highlight some specific search tools for finding health-related Web sites '” directories, search engines, and megasearch engines. Some are specific to the health care environment. Others are generic, all-purpose tools. This is a selective listing.Possible Search Approaches

  1. Following the links from one good, identified site: Similar to following the references found in a key journal article, this can yield nuggets. Given the size of the Internet, however, this is a marginal approach for serious inquiries.
  2. Web directories: Also called subject catalogs, gateways, or guides, these sites provide browsing of hierarchical subject arrangements of selected Web-based information. Site selection is done by humans. Many directories are also searchable. One of the most commonly used general directories is Yahoo! (, which is the largest human-compiled guide to the Web and the oldest, dating from 1994.
  3. Web search engines: These services utilize automatic indexing software to search the Web, locate sites, and index Web pages. All search engines vary as to how they build and maintain their databases, resulting in substantial variability in search results. Therefore, comprehensiveness improves by the use of multiple search engines. However, Lawrence and Giles (1999) report that no search engine provides coverage to more than 16% of the Web and that coverage overall has continued to decline since December 1997.
  4. Megasearch engines: These services send a search query to multiple search engines simultaneously and then present the results. Again, each works in a unique manner and searches on a different combination of resources.

Specialized Web DirectoriesThe Web resources listed here are designed for health professionals, although health consumers may also find them useful. All provide free access. Some require registration and may also offer specialized, for-fee services.

Specialized Web Directory

Description The publisher of CINAHL, the major nursing index to journal articles and related information, provides this selective Web directory at the CINAHL Web site. "CINAHLsources section is designed to provide information on selected World Wide Web sites of interest to nursing and allied health professionals, researchers, and students, among others." HealthWeb is compiled by librarians and information professionals at leading academic medical centers in the Midwest. "Selection emphasizes quality information aimed at assisting health care professionals as well as consumers in meeting their health information needs."
Medical Medical Matrix focuses on identifying and ranking "full content, unrestricted access, Internet clinical medicine resources." Its Editorial Board is drawn from the American Medical Informatics Association Internet Working Group that reviews the rankings given to included sites. Free access; requires one-time registration. Medscape is designed "to provide clinicians and other healthcare professionals with the most timely sources of clinical information that is highly relevant to their patients and practice." It is notable for the access provided to thousands of full-text, peer-reviewed clinical journal articles. Also provided is a searchable drug database of over 200,000 prescription and non-prescription drugs. Free access; requires one-time registration.
Mental Health An award-winning site bringing together all types of Internet resources relating to mental health (Web sites, discussion lists, newsgroups). Web sites are ranked and annotated.
OMNI: Organizing Medical Networked This site from the United Kingdom provides links to sites that serve professionals in varying areas of health care, biomedicine, clinical medicine and allied health. OMNI provides a description and indexing based on the U.S. National Library of Medicine MeSH (Medical Subject Headings).

Specialized Search Engines for Health InformationThese search engines restrict their retrieval to Web pages from sites selected for their quality and utility for health professionals. They search primarily on clinically related sites.

Specialized Web Search Engine


CliniWeb Produced by Oregon Health Sciences University, CliniWeb allows the searcher to enter a term and then directs the search to a list of terms from the MeSH disease classification. The searcher can browse through the hierarchical MeSH results or can search directly. Included are links to search the National Library of Medicine's PubMed database using the appropriate MeSH terms.
Health on the Net (HON) The HON site provides for searching either of a manually created database of evaluated sites or by a traditional Web search engine that limits its retrieval to sites in the medical/health domain. HON is the founding site of the HONcode for ethical development of health information Web sites.
Medical World Medical World Search searches selected sites using a powerful thesaurus capability that minimizes the variability of medical terminology. Searchers are able to refine search results and to query other search engines. Thousands of links to full-text resources are provided. Additional resources include searchable drug information and a dictionary. Links connect to MEDLINE, AIDSLINE, and Toxline. Optional registration provides several additional search features.

General Purpose Web Search EnginesSome of the most popular general search engines are listed below. They can provide very broad, unfiltered retrieval on health-related topics. A few general sites also provide reviews or ratings that may be of use in picking quality resources. A listing of some of these can be found at Internet Sleuth (

Web Search Engine

Description AltaVista provides substantial coverage and the capability to do powerful searches. Anyone with the need to do research on the Web regularly will find it useful to become familiar with Alta Vista and its advanced search techniques. Excite is a popular Web search service, offering a medium-sized index for searching. It is also the search engine used in AOL NetFind and Netscape Search.  Infoseek has a small-to-medium sized index and is an appropriate choice for many general and broad searches. It has a solidly constructed directory of Web sites that has been compiled by human searchers.
Northern Northern Light has a large index and differs from other search engines in that it groups documents by topic. It also provides indexing for documents not typically picked up by search engines. For these "special collection" documents users have the option of paying up to $4 to view the full-text.

Megasearch EnginesMegasearch engines offer great efficiency in that they quickly execute a search against multiple search engines. Their limitation lies in not accommodating the variation in search formats utilized by different search engines.

Megasearch Engine


Ask Ask Jeeves allows you to submit your search question using your own terms, or "natural language," and does not require the search formatting required by most services. In addition to searching its own database, it includes the top ten answers from other search engines and eliminates duplication. The Dogpile megasearch engine will query up to 25 of the search engines supported.
Inference InferenceFind purports to be "the first and only search tool that calls out in parallel all the best search engines on the internet, merges the results, removes redundancies, and clusters the results into neat understandable groupings." It queries six Web search engines, but can be configured to search others. Metafind searches through six search engines returning links and organizing the results.

Other Resources for Searching the WebNumerous resources and tips on Web searching are available. This is a sampling:Finding Information on the Internet: A TUTORIAL (

Tutorial provides guidance for many aspects of successful Internet use, including searching. It is one of the Teaching Library Internet Workshops produced by the University of California, Berkeley, Library.

Learn the Net: Knowledge when you need it. (

Tutorial guide to using the Internet produced by Michael Lerner Productions. "Searching the Web" feature covers basic search engine use. Available in English, French, German, Spanish and Italian editions. Guidelines are given for reproducing this content.

Maze, S., Moxley, D., and Smith, D.J. (1997). Authoritative guide to Web search engines. Neal-Shuman Publishers: New York.

The authors describe how search engines work and the advantages and disadvantages of the various types. Includes comparisons of seven leading, general-purpose search engines.

Search Engine Watch (

This is a key site for up-to-date information on search engines and includes reviews, information on special search assistance features, and search engine tutorials.

ConclusionThe tools described here provide valuable aids to Web searching. As always, analyze your topic and the possible terms and phrases that could be useful. To get the most out of any searching tool, learn its features and the recommended search formats. Remember that the great variability between the design of different search tools and how they work requires that a combination of services be used to get more complete results.


Barbara F. Schloman, PhD, AHIP
Director, Library Information Services
Libraries & Media Services
Kent State University
Kent, OH 44242
E-mail Address: 

© 1999 Online Journal of Issues in Nursing
Article published August 19, 1999


Coelho, P.C. (1998). The Internet: Increasing information, decreasing certainty. JAMA, 280, 1454A.

Lawrence, S. & Giles, C. L. (1998). Searching the World Wide Web. Science, 280(5360), 98-100.

Lawrence, S. & Giles, L. (1999). Accessibility and distribution of information on the Web. Retrieved July 20, 1999 from the World Wide Web:

Network Wizards. (1999). The Internet domain survey. Retrieved June 18, 1999 from the World Wide Web:

Citation: Schloman, B. (August 19, 1999). Information Resources: "Needle in a haystack? Finding health information on the Web." Online Journal of Issues in Nursing.