PageRank leak & increase
We have just set up two separate sites - with one page linking to a page in the other site (here's a picture of the spreadsheet). Then we studied how the linked-to site apparently was able to increase its PageRank. And then we saw how the unfortunate site that linked out suffered a massive PageRank leakage.
You have probably found out by now that the amounts of "PageRank increase" were identical to the "PageRank leak" for each iteration. The values are summed up for every column on the spreadsheet and remains 10 - making the average PageRank 1 - as was explained in the chapter about initial values.
Hagstrøm's first law: For every increase in PageRank, there is an equal and opposite PageRank leak.
Try playing around with the spreadsheet - for instance try a site structure different from the star-configuration used in this example.
You'll find that the structure of the site being linked to doesn't matter. This is a comforting fact really - supposed you linked to a site - and they could drain your site further by rearranging their site!
On the other hand, the structure of the linking site matters a lot. The more internal links the rest of the site passes to this page, the more PageRank this page will have to pass on, and the greater the site's loss of PageRank. So if you have a "Links" page - and want to minimise the PageRank leak - you should have as few internal links to this page as possible - and maybe add some internal links pointing from your "Links" page in order to retain some of the PageRank.
Next: Internal PageRank leak.