The best yet definition of how PageRank works

Details: Thursday, 14 April 2011 18:13; Hits: 302

As search engine optimisers and webmasters we live with the notion of PageRank and its importance to websites (not to mention the psychological impact it has on site visitors) day in day out. Yet the algorithm that governs how PageRank works is so complex as to have created a number of urban myths around it some of which claim (erroneously) that each link you have leading away from your website actually reduces a web page’s PageRank (definitely not true) and that PageRank is the same as SiteRank (it’s not) and will automatically move you higher up the search engine organic pages (it will most definitely not do that).

A great many explanations have, in recent months, attempted to cover how the PageRank algorithm actually works. Some have likened it to a human social network with friends and relatives and figures of authority endorsing each other, others have created a more complicated picture of a society at large voting for specific service related aspects.

The latest attempt is both more scientific and more accessible and it was recently published in the New Scientist.

In a study which shows exactly why explaining PageRank is so difficult when, at the same time, it makes a lot of intuitive good sense we see that the PageRank algorithm mimics the way the human brain retrieves information.

“Our memory for words can be modelled as a network in which each point represents a different word, with each linked to words that relate to it. Psychologist Tom Griffiths and colleagues at the University of California, Berkeley, wondered whether the ease with which the brain retrieves words is similar to the way that websites are ranked by PageRank: by the number of sites that link to them.” says the study.

This is more to be expected than one may assume: The PageRank algorithm is pure maths and mathematics has always been excellent as a language to describe complex aspects of the physical world. Although, perhaps coincidental, the problem of tackling PageRank and using it to serve up search results is one of using a bot that has to try and think like a living, breathing person. It is exactly in this context that the algorithm acts like an artificial intelligence, emulating human judgement, and therefore works like our brains do.

The New Scientist study says that “In tests against other word-retrieval algorithms, PageRank most clearly matched the human model (Psychological Science, vol 18, p 1069). The results suggest human memory studies could be improved by examining the tricks that search engines employ, and vice versa, says Griffiths.”

Search engine optimization is a supremely logical business that follows a logical structure in all the aspects it utilizes. If something makes sense and you get to see it works, it works for good reason even if you cannot always adequately explain it.