7. The Distribution of PageRank Regarding Search Engine Optimisation (continued)

Well Directed PageRank Distribution by Concentration
of Outbound Links

It has already been demonstrated that external outbound links tend to have negative effects on the PageRank of a website's web pages. Here, it shall be illustrated how this effect can be

reduced for the purpose of search engine optimisation by the systematic arrangement of external outbound links.

	We take a look at another hierarchically structured example site consisting of the pages A, B, C and D. Page A has links to the pages B, C and D. Besides a link back to page A, each of the pages B, C and D has one external outbound link. None of those external pages which receive links from the pages B, C and D link back to our example site. If we assume a damping factor d

of 0.5, the equations for the calculation of the single pages' PageRank values are given by

PR(A) = 0.5 + 0.5 (PR(B) / 2 + PR(C) / 2 + PR(D) / 2)
PR(B) = PR(C) = PR(D) = 0.5 + 0.5 (PR(A) / 3)

Solving the equations gives us the follwing PageRank values:

PR(A) = 1
PR(B) = 2/3
PR(C) = 2/3
PR(D) = 2/3

	Now, we modify our example site in a way that page D has all three external outbound links while pages B and C have no more external outbound links. Besides this, the general conditions of our example stay the same as above. None of the external pages which receive a link from pages D link back to our example site. If we, again, assume a damping factor d of 0.5, the equations for the calculations of the single pages' PageRank values are given by

Solving these equations gives us the follwing PageRank values:

PR(A) = 17/13
PR(B) = 28/39
PR(C) = 28/39
PR(D) = 28/39

As a result of our modifications, we see that the PageRank values for each single page of our site have increased. Regarding search engine optimisation, it is therefore advisable to concentrate external outbound links on as few pages as possible, as long as it does not lessen a site's usabilty.

7. The Distribution of PageRank Regarding SEO (continued)

This article reproduced with permission of eFactory.
© 2002 eFactory Internet-Agentur KG Online-Marketing - written by Markus Sobek
PageRank and Google are trademarks of Google Inc., Mountain ViewCA, USA.
PageRank is protected by US Patent 6,285,999.