Google PageRank Changes Will Generate A Webquake?

17 Jun

Posted by: admin in: google, Link Juice, Search Engines, Uncategorized

Initially I planned to name this post “Google changes in the algorithm to calculate PageRank”. However I decided to give it a more marketable name which will reflect more the “Consequences of the Google changes in the algorithm to calculate PageRank”. When I read in a Matt Cutts’s post blog post how Google changed the PageRank algorithm, it thought there will be some changes out there.

Before the algorithm was changed only the dofollow links were considered when the page rank was computed. Lets assume that a page of PR 6 contains 6 links of which 3 are dofollow and 3 are nofollow. Google would consider only the dofollow links when computing how much PR score will be passed by the dofollow links. That would be the PR / number of dofollow links. In our case it is 6 / 3 = 2. In reality not the entire points will be passed, some 10%-15% will be lost.

The new Google algorithm takes in consideration all the links, nofollow and dofollow when dividing the page rank of the source page. The points passed will be PR / (nofollow links + dofollow links). That would be 6 / 6 = 1(reduced to 85%-90% of course). Still the nofollowed pages will get no PR score nor anchor text relevance to the destination pages.

Obviously this move will produce big movements for most of the pages on the web. If this is the only change in the algorithm most of the pages will lose from their page rank even if they don’t contain nofollow links. After all the PR of a page is built based on incoming links. If the pages containing the back links will lose PR the destination page will lose it as well.

People used to play with nofollow/dofollow links in order to direct the page rank points(the term of link juice is also used here) to certain pages. For example wordpress plugins make the links to categories and tags pages nofollows, many sites are through this method to send the link juice to strong pages. This term is called PageRank sculpting.

Before seeing which are the sites will be most disadvantaged by this move, lets say that page rank is just one of the many factors used by google to decide which are the best results for what you are looking for. A lowered PR does not necessarily means less visitors sent by search engines.

The most affected sites are of course sites containing nofollow links. Right now I’m thinking to the following categories:

sites based on user generated content – digg, twitter, youtube clones and many many more. Lots of web 2.0 sites contains no follow links and user generated content
wikipedia – maybe I should put it in the above category, but since for many keywords wikipedia is the first result I wanted to put it separately. Wikipedia pages contains a list of external links at the end.
forums – many forums shows the links from posts as no follow in order to avoid spam
blogs – most of the blogs have no follow link comments.

Then it comes the second category of pages, which used to have their PR built by the dofollow links from the sites from the above categories. However the first 3 categories should be excluded, because they have most of the links as nofollow, they don’t really pass page rank points. The only remaining category is represented by the blogs with their in text or in context dofollow links. Since they have lots of comments the pages will lose their PR and consequently will pass less.

Unfortunatelly, Matt does not specify when this change was done. I don’t think the current PRs reflect it, but I assume the next PR change will bring some big changes.