Most of the search engines return results with confidence or relevancy rankings. In other words, they list the hits according to how closely they think the results match the query. However, these lists often leave users shaking their heads on confusion, since, to the user, the results may seem completely irrelevant.
Why does this happen? Basically it’s because search engine technology has not yet reached the point where humans and computers understand each other well enough to communicate clearly.
Most search engines use search term frequency as a primary way of determining whether a document is relevant. If you’re researching diabetes and the word “diabetes” appears multiple times in a Web document, it’s reasonable to assume that the document will contain useful information. Therefore, a document that repeats the word “diabetes” over and over is likely to turn up near the top of your list.
If your keyword is a common one, or if it has multiple other meanings, you could end up with a lot of irrelevant hits. And if your keyword is a subject about which you desire information, you don’t need to see it repeated over and over–it’s the information about that word that you’re interested in, not the word itself.
Some search engines consider both the frequency and the positioning of keywords to determine relevancy, reasoning that if the keywords appear early in the document, or in the headers, this increases the likelihood that the document is on target. For example, one method is to rank hits according to how many times your keywords appear and in which fields they appear (i.e., in headers, titles or plain text). Another method is to determine which documents are most frequently linked to other documents on the Web. The reasoning here is that if other folks consider certain pages important, you should, too.
If you use the advanced query form on AltaVista, you can assign relevance weights to your query terms before conducting a search. Although this takes some practice, it essentially allows you to have a stronger say in what results you will get back.
As far as the user is concerned, relevancy ranking is critical, and becomes more so as the sheer volume of information on the Web grows. Most of us don’t have the time to sift through scores of hits to determine which hyperlinks we should actually explore. The more clearly relevant the results are, the more we’re likely to value the search engine.