Thursday 29 May 2008

Google opens up about Search Quality

A recent posting on the Official Google Blog by a senior search engineer reveals some more information about how the Google search engine ranks sites and the ongoing work that goes into improving ranking results. As the article says, the many ranking criteria that drive the search algorithms remain a trade secret to protect themselves from competitors and abuse of the system, but more insight is provided here.

It outlines all the different factors that can make an automatic assessment of a web page a difficult task and the need to match a short search query with the most relevant results within milliseconds. This can only have become harder with the introduction of 'universal' search results over the past year. The original PageRank algorithm remains a core part of Google's ranking criteria but this is combined with other issues such as different models to cope with language, query usage, recency, personalisation and regional results.

A team of engineers works on the evaluation of search results quality and many changes or enhancements can be made during the year - for example, in 2007, over 450 new improvements were introduced, ranging from simple improvements to more complicated changes. The article reveals that significant changes were made to the PageRank algorithm in January which could have dramatically affected the rankings for some websites.

Other teams work on new features and new user interfaces, with the latter group assisted by a team of usability experts who conduct user studies and evaluate new features with Google users around the world. Then, of course, there is the team of engineers who focus on fighting webspam and other types of search engine abuse, such as hidden text to off-topic pages stuffed with irrelevant keywords and other attempts to fix ranking positions. The team may spot new spam trends (or have them reported to them) and then works to counter those trends within the ranking algorithms.

Overall it's a well-written, clearly explained introduction to what goes on 'behind the scenes' at Google and indicates a new willingness to share some of this information with the wider public. It's also a sign of better PR being undertaken with possibly an attempt to avert some of the more negative press and comment that a company of Google's size and prominence starts to attract.

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