How much is the "link dilution" loss?

[greentop]

I'm fairly new to SEO, and am hoping you can help answer a question: How quickly does link-value decrease when the number of links on a page increases?

For example, imagine that two external pages with equal SE-status link to my page, but one external page has 5 total links (mine plus 4 others) and the other has 50 links. Is the dilution loss "linear" so that, for improving my SE-rank the second would count 1/10 as much because instead of my link being 1-of-5 (= .20) it's 1-of-50 (= .02), so with 10 times the links my page gets 1/10 as much credit? Or is the dilution less, so instead of a dilution of 1/10 it is 1/8 or 1/5 or 1/3 or...?
I realize that you don’t know the mathematical SE-algorithm formula, so exact numerical answers aren’t possible, but do you have estimates for "how quickly"?

Here is my reason for asking, and why this question seems relevant for all site designers:
I don't control the incoming links from external sites, but I'm wondering about links from my homepage to my own pages. I assume a similar “numerical dilution of link-value” occurs with internal links within a website, so whether the dilution is 1/10,... or 1/3 is signficant for decisions about website structure.

GT

[Robert_Charlton]

...I assume a similar “numerical dilution of link-value” occurs with internal links within a website, so whether the dilution is 1/10,... or 1/3 is signficant for decisions about website structure.

greentop - As a very rough way of looking at it, I've always assumed for site design purposes that the fraction of a page's link-value passed on by a single link is inversely proportional to the number of links on the page. And you're right, this is very significant for decisions about structure.

This doesn't take into account other internal linking patterns, deep links, etc, but it's not a bad ballpark way to start looking at it.

Take a look at this post where I address a question that has similar issues to yours...

Does a new theme in your site affect previous ranking?
http://forums.searchenginewatch.com/showthread.php?p=43128#post43128

[PuneetJvw]

Don't think about the PR or the crawlers.

It depends really upon you, google only says that you should not have more than 100 links on a page.

Have the links on your page keeping in mind your website visitors and nothing else.


Regards/Puneet M.

[greentop]

Robert Charlton says,
>As a very rough way of looking at it, I've always assumed for site design purposes that the fraction of a page's link-value passed on by a single link is inversely proportional to the number of links on the page. And you're right, this is very significant for decisions about structure.

You say "I've always assumed... inversely proportional" but does anyone know? I've seen the general principle -- that link value decreases if there are lots of links on the referring page -- but this is vague. I've wondered how they know this principle, and what is known about "HOW MUCH the link-value decreases."

Thanks for the feedback. Your post in the other thread is exactly what I was thining about, with "10 links to 20 links" producing a large link-dilution (but how large?) while "from 10 to 11" would be negligible.

GT

[Robert_Charlton]

PageRank
From Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/PageRank

In other words, the PageRank conferred by an outbound link L( ) is equal to the document's own PageRank score divided by the normalized number of outbound links (it is assumed that links to specific URLs only count once per document).

(Note that the words "assume" and "suppose" are used a lot when talking about search engines, or they should be, as no... we really don't know for sure.)

[Marcia]

You might want to run a few test scenarios through Phil Craven's Page Rank Calculator (http://www.webworkshop.net/pagerank_calculator.php) and see what comes up.