Online search engines produce varying results
By Russell Shaw
Gannett News Service
Perhaps you're researching college tuition savings plans or romantic hotels in Tahiti. Internet search engines, such as Google (www.google.com) and directories, such as Yahoo! (www.yahoo.com), will help you find Web sites and other online resources with this information. If you use any of more than a dozen such search services, you will probably find that the results you get from each are different. That's because not all search services work the same way.
Search engines do share one trait. No matter what search service you use to scour the Web, the search site does not actually "go to" the Web and pore through its more than 2 billion Web pages. Instead, search sites examine listings of other sites and Web pages included in their databases.
Search services find these sites and pages during periodic sweeps, or "crawls," of the Web. New sites are added to the database, and most search services offer Web site owners the opportunity to submit their own sites. At times, such a step can add a site to a search engine's database before the "crawler" will find it.
"There are three major ways search engines gather listings," said Danny Sullivan, editor of SearchEngine-Watch.com (www.searchenginewatch.com), a guide to online search utilities. "Not every search engine has the same collection of documents. That, alone, causes differences. Secondly, every search engine has its own unique way of sorting through its documents."
Sullivan added that to build a searchable database of sites, services such as Google and AltaVista (www.altavista.com) use "crawlers" to automatically find pages. But search resources such as Yahoo! and LookSmart (www.looksmart.com) use human beings to catalog Web sites. Overture (www.overture.com) is an example of a search site that includes listings from advertisers that pay to have their sites listed when you perform a search that includes words related to what the sponsor's site is about.
Some search engines crawl the Web more frequently, or more thoroughly than others. That's one key reason why search results are so different from engine to engine.
Depending on what search engine you use, all these differences can lead to significantly different search results.
Take a search, for example, for the terms "Tahiti" and "honeymoon."
Google's computers looked through all the Web pages stored in its database and retrieved the pages that contain both words — about 22,300 pages. The first of these listings was Tahiti Resort Guide (www.tahiti-guide.com).
Yet, the same search on AltaVista yielded only 5,941 results. Lycos (www.lycos.com) retrieved 34,968 pages, and AllTheWeb (www.alltheweb.com) dished up 11,360. There was very little overlap between the first several sites listed on any of the results pages.
Why were the results so different? In addition to how these search sites rank the Web pages in their database, they tend to search their databases differently when you submit a keyword.
To find Web pages that match your search, sites such as AltaVista rank Web addresses in part by the number of times your search terms appear on a given page, how high up on the page these words occur, and if these words are in the same sentence. The theory behind this method is that a Web page that includes your search terms near the top of the page is likely to include the information you are seeking.
But Google's rankings rely somewhat on how many other sites link to the site or page that contains your search terms. In other words, Google ranks more popular sites ahead of other sites because it believes that the information on these sites has more value.
With so many differences in the way search sites perform, what's a searcher to do?
Among many search experts, Google is the current and clear favorite.
"Results at Google are generally more relevant than you'll get at some of the other engines," said Robin Nobles, a contributing writer for the Hattiesburg (Miss.) American and author of two books about Web searching. "It also does a good job of updating its index on a very regular basis."
If Google doesn't give you the information you want, it may be time to use a for-pay search service, such as Dialog (www.dialog.com), your local newspaper's archive or a search site specifically related to your interest. Google and other search tools can point you to some of these resources.
