PageRank (or PR) leakage
Whether PageRank Leakage exists or not, is a question of semantics. The PageRank for a given page is solely determined by the inbound links.(1) However, as the spreadsheet will show, an outgoing link can drain the entire site for PageRank.
Then we studied how the linked-to site was able to increase its PageRank. We will now look at how the linking site fares.
The Page Ranks of the 4 other page have dropped, however, since they are now getting a smaller share of Page5's PageRank. The loss equals 0.425 per page for a total of 0.17 - exactly as we predicted.
|Many iterations later|
And notice another curious thing: For every iteration the leaking page (i.e. Page5) has the highest PageRank in this mini-site. The other 4 pages have even lower PageRank because Page5 isn't doing its part. This slight difference in PageRank will probably not have an effect in the real world - but if anybody tells you their pages perform better when they link out - give it a thought.
A final note: This does not mean that you shouldn't link out.(2) PageRank is only one part of Google's algorithm. I'm personally convinced Google have lots of other ingredients in their secret sauce, which will reward sites that links out.
And now for The Big Picture