Google Rankings Behind The Scene
June 7, 2007 by Gaman
The New York Times has published an interesting article taking you behind the scene into how Google’s search quality team works to improve Google search results quality.
It’s a rather long but well written article which tells us how the team job is ongoing and is never done. They don’t make several changes every few months like some people think but more like a few changes every week.
Another interesting issue the article talks about is QDF or “query deserves freshness” score or value to help fresh pages do well in the search results but yet not over shadow the older pages.
Google uses over 200 factors to determine the ranking of a page and a PageRank is just one of them.
As Google compiles its index, it calculates a number it calls PageRank for each page it finds. This was the key invention of Google’s founders, Mr. Page and Sergey Brin. PageRank tallies how many times other sites link to a given page. Sites that are more popular, especially with sites that have high PageRanks themselves, are considered likely to be of higher quality.
Mr. Singhal has developed a far more elaborate system for ranking pages, which involves more than 200 types of information, or what Google calls “signals.” PageRank is but one signal. Some signals are on Web pages — like words, links, images and so on. Some are drawn from the history of how pages have changed over time. Some signals are data patterns uncovered in the trillions of searches that Google has handled over the years.
“The data we have is pushing the state of the art,” Mr. Singhal says. “We see all the links going to a page, how the content is changing on the page over time.”
Increasingly, Google is using signals that come from its history of what individual users have searched for in the past, in order to offer results that reflect each person’s interests. For example, a search for “dolphins” will return different results for a user who is a Miami football fan than for a user who is a marine biologist. This works only for users who sign into one of Google’s services, like Gmail.
Matt Cutts, one of the Web Spam team members has a post up over at his blog in response to the article. He basically explains five things you didn’t know about Google search.