> I know if there are 10 outbound links on a page and 5 are to robots.txt excluded pages it's still divided by 10 (not 5) so half is going to waste,
> but Calum, what are you referring to by PR being lost?
The half going to waste doesn't recycle within your link network. I imagine it ends up in the rank source (due to normalisation), but looking at a PR feedback loop situation quite a lot of raw PR can be lost from your pages by a REP excluded URL or a 404.
The interetsing thing is that the behaviour seemed to change last Friday. Letting 404s suck PR from a site does give an incentive to keep an eye on link rot, but I suppose that's not really a Google objective.
More_Traffic_Please, yes the raw PR would be split evenly and the Toolbar PR would be only slightly less than the linking page.
> It does not take much for a site to get to a PR4. That changes the higher you get. Maybe the splitting of PR does not happen until PR6 or above.
I recommend "The Anatomy of a Large-Scale Hypertextual Web Search Engine" by Sergey Brin and Lawrence Page, then "The PageRank Citation Ranking: Bringing Order to the Web" (same authors, and then some research into logarithmic scales. Only then, I recommend considering the affect of aspects like REP/404s on PR and the analyses of PageRank feedbank loops using log scales (which also causes confusion). I haven't come across any rigorous testing that demonstrated a change in the log scale with PR, or a change in the general flow of PageRank from the original Google papers.
johnnydequino, if I understand the structure correctly then it's PR nuetral. Some pages gain a little, and others loose a little but it averages out. You're not creating PR there, just moving it around. (Marcia once drew a nice parallel with thermodynamics.)
eztrip, the raw PR is divided by 50, but n^5 / 50!= 0.5 (between 3.5 and 4.0 by my calculations). Three links from Toolbar PR5 page (5 >= PR < 6) should give Toolbar PR4 or Toolbar PR5.
It is very important to remember that we're talking purely about pages; a link from a PR2 page on a PR10 site is just a link from a PR2 page (else we'd all be putting up geocities sites!).
Unless stated otherwise, I talk about a destination URL's PageRank without taking into account any PR feedback loop within the site.
[edited by: ciml at 7:15 pm (utc) on Aug. 14, 2003]