|
These are gateways to medically
orientated websites which meet certain quality criteria.
| Table 2. Evaluated websites |
OMNI |
OMNI is a UK-based service with published 'Guidelines for Resource Evaluation'.
When you perform a search at the OMNI site you are searching the OMNI catalogue of
descriptions of biomedical resources that meet OMNI evaluation
criteria. |
| Medical Matrix |
Medical Matrix is a US site which offers resources catalogued into directories,
as well as search facilities and Medline access. Registration is required, but is free. |
Top
The key difference between directories
and search engines is that human beings are involved in the selection of sites for
inclusion in directories (as opposed to search engines which employ 'robot' programs to
roam the net, indexing the sites).
People often find directories easier to
use, because they mirror traditional hierarchical methods of finding information (similar
to the system you might use when using a library).
| Table 3. Directories |
| Open Directory Project |
Superb and an excellent starting point for a beginner. The Oingo search engine is another interesting way to access
the Open Directory |
Yahoo
Yahoo UK |
An Internet classic which combines a directory tree with a search engine. There
is a UK-specific Yahoo site as well |
| Argus Clearinghouse |
Contains links to evaluated Internet subject guides |
| Internet Public Library |
This has a growing number of guides to subject areas on the Internet. If there
happens to be a guide relevant to your search then you're onto a winner. |
| WWW Virtual Library |
Showing its age with an old-fashioned interface, but contains an absolutely
massive number of catalogued links |
| Galaxy |
A directory service with a bias towards professionals |
Search engines maintain huge databases
of web pages, compiled with the use of 'robot' programs that access and classify web
pages, as well as by web authors submitting their site addresses for inclusion. Using
search engines requires a certain amount of skill, and it is worth spending some time on
the Search Engine Tutorial to acquire this.
Search engines employ a common format,
in which you enter a search string (a set of words relating to the topic you are
researching) and the search engine generates a list of web pages. Each engine will search
its own index and at present no single search engine covers more than about a third of all
possible web pages. This means that it is best to use more than one engine.
Some search engines do not have their
own compiled index, but instead send search strings to a number of other search engines.
They then collate the results, eliminating duplicates. These are called metasearch engines
and they are often valuable when you are doing a quick search - however, their performance
is a bit unpredictable if you want to do more complex searches.
Often a search can produce many
thousands of 'hits'. You will need to read the instructions for each search engine to
refine your search. Table 4 lists a number of search engines and their characteristics.
Other sites worth visiting include HealthFinder (US government consumer guide), the National
Library of Medicine's MedlinePlus and the SearchEngineWatch links page
to the major search engines.
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