PageRank Leak

PageRank (or PR) leak

One of the most vehemently debated subjects is whether or not there is such a thing as "PageRank leak".

The curious part is that many people will deny the existence of PageRank leak - and at the same time believe that they can increase their PageRank by having a well-linked site - without realising that this is the other side of the coin:

Hagstrøm's first law: For every increase in PageRank, there is an equal and opposite PageRank leak.

Simple setup with 5 pages For this demonstration let's assume two sites - both with a simple structure like the picture to the left.

Simple setup: 2 site with 5 pages each
How to specify two sites with 5 pages each
The set-up is done on the spreadsheet like this:

The result is that both sites have a total PageRank of 5. If you haven't got the spreadsheet, you can see the result on this spreadsheet.

Introducing a leak from Page5 to Page8
How to link from one site to another
Now let's assume that we add a link from Page5 to Page8 in the other site (image to the right). Before looking at the spreadsheet, let's try and guess, how much the increase / leak will be:

Guess: Page5 had a PageRank of 1 in the first iteration. Since Page5 is now linking to 5 pages (4 internal pages + Page8) - and with a damping factor of 0.85 - we would assume the loss to be 0.85 * (1/5) = 0.17 - i.e. negligible.

Now let's stop guessing and take a closer look at

Here's a PageRank leak to my wife's site with homemade knitted baby-clothes: Børnetøj. If you can read Danish, if you live in Copenhagen and if you have a baby in the exact size, you can make a great deal.