Do external links drain PageRank?

[Florakel]

Example: A page has 100 links, 90 internal links and 10 external links. The page has a Google internal PR of 1000.

The question is: Is the pagerank that flows to the internal links being calculated taking into account all links on the page (internal + external) or only the 90 internal links? E.g. is the PR that flows to the internal links 1000/100 or 1000/90? Are links to external sites "votes" that do not affect the internal PR flow?

Disclaimer: I understand that the maths behind the PR algo are more complex. This simplified example only serves to explain my question.

[Florakel]

Agreed.

I believe it is important to have a "natural" link scheme in order to rank well. Sites that only receive but don't give might look unnatural. There must be some kind of "reward" in Google's algorithm for sites that link out to relevant, quality resources.

[Florakel]

Yes, I agree that it cannot be in Google's interest to "penalize" a site for linking out to high quality, relevant resources. Google's algorithm is based on sites linking to each other so why should they discourage people to do that. So, thumbs up for high quality, relevant, editorial, ext. links; thumbs down for low quality ext. links.

[TellThemEverything]

Ah, the classic unanswerable question.

Many people have asked - and many people have guessed at the answer. There are numerous ways people have approached this "problem" - some nofollow outbound links, some use javascript to hide the links entirely from bots.

I keep coming back to the advice - what would you do if there were no search engines?  Building your site to make sense for people is still the advice that google offers.

Personally, I like linking out to relelvant topical sites from my ecommerce sites. I'm not being stingy with links to helpful places. I do however nofollow all my comments - for obvious reasons.

[wissamdandan]

Dear Florakel,

Google clearly mentioned couple of times that PR will be distributed equally to all links.

so to go back to your math, PR will be divided by 100 (1000/100). I encourage to link out to authoritative sites, because it will also tells google to which neighberhood you belong to.

[StalkerB]

According to your example, external links drain page rank.

Every link, whether internal or external gets the same juice to it.

Theoretically

EDIT: Better show my working since it didn't save last time

Whiteboard Friday - http://www.seomoz.org/blog/whiteboard-friday-the-juice-is-loose

No Follow advice (but has nice diagrams to help you understand) - http://www.seomoz.org/blog/google-maybe-changes-how-the-pagerank-algorithm-handles-nofollow

Bonus thoughts - http://www.seomoz.org/blog/pagerank-link-patterns-the-new-flow-of-link-juice