Google likes directory sites
Hardin MD Notes, Jan 3, 2000
In looking for information on the web, there have long been two basic approaches -- Computer-driven search engines work best for "needle in a haystack" searches and people-produced search directories work best for browsing in broad subjects. In the last couple of years, this separation between search engines and search directories has begun to break down, as several of the standard search engines have added nominal search directory components.
Using Google to find directory sites
Experienced web researchers soon learn, in looking for information on specialized subjects, that the key is often finding a well-maintained "list of links" on the subject, otherwise known as a directory site. Finding these, however, can be difficult. Since its conception in 1995, the purpose of the Hardin Meta Directory of Internet Health Sources (Hardin MD) has been to provide access to the best directories in 38 clinical medicine specialty fields.We've recently discovered that searching in Google for the names of these medical specialties turns up a remarkable phenomenon -- Almost invariably, in the first 100 hits in the Google search (out of several thousand hits total), many of the directory pages appear that we list in the Hardin Meta Directory! Why? Because the Google search engine is smart! -- Intelligent humans learn from experience with the Net that directory sites are important, and so they do the obviously human-smart thing and put links to directory sites on their pages. Google, finding these many links, is able to take advantage of this accumulated human-smartness, and that's why so many directory sites come to the top in Google searches.
How do we know?
A search (done in November, 1999) illustrates our theory that Google likes directory sites -- The Hardin MD Hematology page lists 15 directory sites. 8 of these have the word "hematology" in the title. Searching in Google for the word "hematology" pulls up a list of about 31,000 hits. 7 of the 8 sites on the Hardin MD Hematology page are in the first 100 of these. Our preliminary study of other Hardin MD subjects gives comparable results -- The first 100 hits in a Google search for a Hardin Meta Directory subject word usually includes 4-6 of the directory sites listed on our page.
How about the Hardin Meta Directory?
A further confirmation of the idea that Google likes directory sites is the placement of Hardin MD pages in the Google searches we've done. Being a "meta directory", or "directory of directories," we might theorize that the Hardin Meta Directory would be especially high in Google rankings, and that was the case in our small survey done in November, 1999. In a sample search for 21 words that appear in Hardin MD page titles (e.g. cardiology, dermatology, nephrology), Hardin MD averaged about 25th; in 2 cases it was #1, and in 7 cases it was in the top 10. Comparing these rankings to the multi-subject directory sites in the Hardin MD, which are linked to from several Hardin subject pages, shows that none of them has rankings quite as high, with the highest (MedWebPlus) averaging about 35th. We should stress, however, that this slightly higher ranking of Hardin MD pages is a relatively minor phenomenon, compared to the discovery that directory sites in general rank so high in Google. The ranking of any one directory site (including Hardin MD) in Google searches will undoubtedly fluctuate from month to month. The overall high ranking of directory sites in general, however, seems likely to remain stable. Our point is not that Google likes the Hardin Meta Directory, but that Google likes directory sites!
Hardin Library for the Health Sciences, University of Iowa
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