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Outbound links
A hole in the bucket?

 7:20 pm on Aug 22, 2004 (gmt 0)

I recently read an article available on the Web. In the section about outbound links the author plainly states that Outbound links leak PageRank. I searched this forum looking for corroboration to this claim, and did not find any. I have to admit that I am still something of a novice, and might not have learned from these discussions all that someone with a deeper understanding of the subject might have.

This subject particulary interests me because I am interested in developing a Web site which would by its nature contain very many links to pages found on external sites. I am now worried that my site would, in S.E.O. terms, be like a bucket with a hole in it!

Are my concerns justified?

[edited by: martinibuster at 10:08 pm (utc) on Aug. 22, 2004]
[edit reason] Edited for specifics [/edit]



 12:57 am on Aug 23, 2004 (gmt 0)

PR does leak when you link out to pages. There's no doubt, unless G's radically altered the way they calculate PR.

The thing is, there are advantages to linking out to other pages. So you have to balance out the advantages and disadvatages. The best way to do that is to experiment and rea dthis board. Have fun doing both :)


 2:17 am on Aug 23, 2004 (gmt 0)

Pagerank does not "leak." Pagerank is determined by other sites linking to you. Do you think penalizing a site for linking is a good idea?


 2:49 am on Aug 23, 2004 (gmt 0)

Two contradictory answers from two "Full Member"s! when karmov states

There's no doubt, unless G's radically altered the way they calculate PR

he seems to indicate familiarity with old papers describing robot algorithms, whereas Teknorat merely provides philosophical justification for his argument.


 2:55 am on Aug 23, 2004 (gmt 0)

If you allow the search engines to determine how and what you write or to whom you link ... its game over for the world wide web!

Link to whomever you choose and let the "PR" chips fall where they may. You'll probably be surprised how well your site does. :)


 3:12 am on Aug 23, 2004 (gmt 0)

pagerank does leak in the sense that a page's outgoing links will decrease that page's available PR for redistribution throughout the same site.


 3:20 am on Aug 23, 2004 (gmt 0)

when people say that outbound links 'leak pr' they referred to the following;

a page with a PR of 5 links to two internal pages and one outbound link. That means that 2/3s of the pr goes to internal pages and 1/3 is 'leaked'.
The actual pages pr is NOT affected. But the PR wealth of your whole site may be reduced.

Outbound links are usually good for the user and is it is said to be now an important part of googles algo.

In short. Create your site for your users.
Build a structure that promotes good pr distribution but does not inhibit the purpose of the page.

Patrick Taylor

 4:00 am on Aug 23, 2004 (gmt 0)

The actual pages pr is NOT affected. But the PR wealth of your whole site may be reduced.

Linking off a page "per se" reduces its PR. That is a mathematical certainty.


 4:20 am on Aug 23, 2004 (gmt 0)

page1 has 3 links to it.

therefore let us say for arguments sake that page1 has a pr of 3.

Now if page 1 links out to 3 sites the pr value of those links is split into 3. If it links out to 4 sites the pr is split up even more. Therefore a link to your site on a pr 4 page with 2 links is worth more than a link from a pr 5 page with a million links on it.

Now the value of the links going out from the page decrease with the number of links but page1's pr is not affected. page1's pr value is determined by what links to it NOT by what it links to- the value of the links from page1 to other pages is determined by page1's own pr and the number of links.

I probably didn't write that very well but end of story.

Oh and Gsmith just because it says "Full Member" next to my name doesn't mean I actually know anything. ;)


 5:03 am on Aug 23, 2004 (gmt 0)

Try this:
1) Pick a page on your site
2) Note the PR
3) Add 300 or so outgoing links on the page
4) Make sure the incoming links to that page do not change
5) Wait for the the next PR update or two
6) Note what happens to the PR for that page ..... NOTHING (assuming other things remain the same).


 5:06 am on Aug 23, 2004 (gmt 0)

A-thank you. There you go, anyone who still thinks it "leaks" can try it themselves. :D


 5:30 am on Aug 23, 2004 (gmt 0)

"Pagerank is determined by other sites linking to you."

No. Pagerank is determined by what pages link to you.

And this includes pages on your own domain.

If you have a PR4 page... with three links off of it going to NASA, you will still have a PR4 page next update. If instead you have three links that go to other pages that link back to this PR4 page, this page will be PR4+ next update.

It's not complicated, even though people want to make it so. All your pages can cast votes. You can vote for pages that vote for you (either your own pages or something like a Yahoo category that links to you); or you can link to pages that in no way link to you, like linking to the Google main page.

If you do the latter instead of the former you will have a lower pagerank. That is the end of the story.

Linking to pages that in no way link back to you will result in you having lower pagerank compared to if you link to pages that do link back to you.

Patrick Taylor

 5:31 am on Aug 23, 2004 (gmt 0)

You can say what you like (I don't mean steveb). The plain simple fact is that a link from a page passes out some of its PR, otherwise how could the page it links to receive any? According to that (incorrect) model (of a page holding on to the same amount of PR irrespective of links out - suggested above) the total amount of Google PR on the web would be ever-increasing in relation to the number of links off all the web's pages. No. Overall, it's a factor of the number of pages on the web that are indexed by Google, and links are just a way to redistribute it.

[edited by: Patrick_Taylor at 5:43 am (utc) on Aug. 23, 2004]


 5:42 am on Aug 23, 2004 (gmt 0)

"The plain simple fact is that a link from a page passes out some of its PR, otherwise how could the page it links to receive any?"

That is not how it works. Don't make something complex that is very simple.

If ten people vote for me, it just means that I now have a right to cast eight votes, while still having a value of ten myself.

George Bush was "elected" President via votes.
He appoints Cabinet Members (main subdirectory pages).
The Cabinet Members hire workers (individual html pages).
Nothing in this process lowered the power of the President.


 5:46 am on Aug 23, 2004 (gmt 0)

Yeah sorry about "Pagerank is determined by other sites linking to you." I meant of course pages, and yes that includes your own pages.

Patrick Taylor I don't quite get what you're saying. Anyway the bottom line is:

Linking out does not affect your SERPS EXCEPT for when you are changing the number of links and you are also linking internally in which case those links would be worth less.

Patrick Taylor

 5:48 am on Aug 23, 2004 (gmt 0)

The voting metaphor is misleading. A real vote costs nothing, but a link out costs PR - a redistribution mechanism. It's a plain simple calculable fact. If it wasn't, Google would explode like a huge over-inflated PR balloon.


 5:48 am on Aug 23, 2004 (gmt 0)

>The plain simple fact is that a link from a page passes out some of its PR, otherwise how could the page it links to receive any

Yes of course but it doesn't entail that the original page loses some of it's PR merely because it links out. This only comes into play when we factor in where the linked-to pages themselves link out to and whether they link back to the original page or to pages 'near' it.


 6:09 am on Aug 23, 2004 (gmt 0)

Patrick Taylor- You are incorrect.


 6:17 am on Aug 23, 2004 (gmt 0)

>>>>I am interested in developing a Web site which would by its nature contain very many links to pages found on external sites. I am now worried that my site would, in S.E.O. terms, be like a bucket with a hole in it!

Its quite possible to mask the outbound links so they do not "leak" pr.

Patrick Taylor

 6:41 am on Aug 23, 2004 (gmt 0)

Patrick Taylor- You are incorrect.

I don't think so. The total amount of Google PR available throughout the web is created only by the presence of pages in Google's index. That total is not altered by links. Links in themselves do not create any additional total PR. They are simply a redistribution mechanism. This is how I understand it.

So it follows that a page must actually spend a proportion of its PR when it links to another. And 2 pages that link to each other are wasting whatever joint PR they have through the dampening factor.

I'm not commenting here on the merits or demerits of outgoing links - only on the fact that an outgoing link "per se" costs PR.


 6:52 am on Aug 23, 2004 (gmt 0)

Ok- I see what you're saying. However do you have any proof that this is the way PR works?

Patrick Taylor

 6:55 am on Aug 23, 2004 (gmt 0)

The Brin and Page paper, I would imagine.


 7:03 am on Aug 23, 2004 (gmt 0)

2.1 PageRank: Bringing Order to the Web
The citation (link) graph of the web is an important resource that has largely gone unused in existing web search engines. We have created maps containing as many as 518 million of these hyperlinks, a significant sample of the total. These maps allow rapid calculation of a web page's "PageRank", an objective measure of its citation importance that corresponds well with people's subjective idea of importance. Because of this correspondence, PageRank is an excellent way to prioritize the results of web keyword searches. For most popular subjects, a simple text matching search that is restricted to web page titles performs admirably when PageRank prioritizes the results (demo available at google.stanford.edu). For the type of full text searches in the main Google system, PageRank also helps a great deal.
2.1.1 Description of PageRank Calculation
Academic citation literature has been applied to the web, largely by counting citations or backlinks to a given page. This gives some approximation of a page's importance or quality. PageRank extends this idea by not counting links from all pages equally, and by normalizing by the number of links on a page. PageRank is defined as follows:

We assume page A has pages T1...Tn which point to it (i.e., are citations). The parameter d is a damping factor which can be set between 0 and 1. We usually set d to 0.85. There are more details about d in the next section. Also C(A) is defined as the number of links going out of page A. The PageRank of a page A is given as follows:

PR(A) = (1-d) + d (PR(T1)/C(T1) + ... + PR(Tn)/C(Tn))

Note that the PageRanks form a probability distribution over web pages, so the sum of all web pages' PageRanks will be one.

PageRank or PR(A) can be calculated using a simple iterative algorithm, and corresponds to the principal eigenvector of the normalized link matrix of the web. Also, a PageRank for 26 million web pages can be computed in a few hours on a medium size workstation. There are many other details which are beyond the scope of this paper.
2.1.2 Intuitive Justification
PageRank can be thought of as a model of user behavior. We assume there is a "random surfer" who is given a web page at random and keeps clicking on links, never hitting "back" but eventually gets bored and starts on another random page. The probability that the random surfer visits a page is its PageRank. And, the d damping factor is the probability at each page the "random surfer" will get bored and request another random page. One important variation is to only add the damping factor d to a single page, or a group of pages. This allows for personalization and can make it nearly impossible to deliberately mislead the system in order to get a higher ranking. We have several other extensions to PageRank, again see [Page 98].

Another intuitive justification is that a page can have a high PageRank if there are many pages that point to it, or if there are some pages that point to it and have a high PageRank. Intuitively, pages that are well cited from many places around the web are worth looking at. Also, pages that have perhaps only one citation from something like the Yahoo! homepage are also generally worth looking at. If a page was not high quality, or was a broken link, it is quite likely that Yahoo's homepage would not link to it. PageRank handles both these cases and everything in between by recursively propagating weights through the link structure of the web.

Ok so where does it say what you are saying?


 7:25 am on Aug 23, 2004 (gmt 0)

as far as the outbount links are relevant to your pages content and offers more information to the end user nothing will happen to your PR, i believe ,though if your out bount links from a page that offers widgets to a page that offers fried tomatoes that is not a good idea


 7:27 am on Aug 23, 2004 (gmt 0)

No skanky links now kiddies! :P


 7:30 am on Aug 23, 2004 (gmt 0)

PT - you are incorrect, not linking out can lift or lower your PR as well as linking our.

1.case - increase of pr
if you link to pages which somehow (directly/indirectly) link back to you, will give you more pr in some cases.

2.case - decrease of pr
if you link to pages which never link back to you then you lower the pr that is passed to internal pages and pages that link back to your page, so you indeed are loosing pr on that page.

it is hard to say which outlinks can give you back pr, especially if it is passed indirectly. but if 2. is the case then you are really loosing pagerank, whereas the pagerank is not lowered by linking out but by passing pr to pages that will never pass it back to you. however, if you are trying to hoard pr then google might spot you as a pr hoarder and might punish you.

incorrect is that a page is loosing pr because an outlink is "costing" pr, correct is a page is loosing potential pr if an outlink never passes pr back directly or indirectly.

the total amount of pr is not determined by the total links on the web, but by the total pages. so additional outlinks do not affect anything but the pr a linked page is receiving and this can affect the linking page back.

deciding whether an outlink should happen or not is not a question of pagerank but of other things.
1. is it pointing to a bad neighbourhood
2. is it a useful page

an outlink MAY help you in the serps, though, but not many know how.


 7:39 am on Aug 23, 2004 (gmt 0)

well, google links out to 4,285,199,774 pages, and still has aPR of 10 ;)


 8:07 am on Aug 23, 2004 (gmt 0)

If there is any leakage I believe it to be so small that, unless taken to an extreme, outbound links will not reduce your PR as seen on the toolbar.

Patrick Taylor

 8:18 am on Aug 23, 2004 (gmt 0)

Well I've just been reading up, and trying out a few things in the Google Page Rank Calculator I have to use, as I am not good at maths. In Google's own words "do one thing, and do it really really well." SEO is not my thing, as I've just reminded myself. So... I apologise if I'm wrong about this, and I now think I am, in terms of the effect of outgoing links on the overall sum of PR.


 8:27 am on Aug 23, 2004 (gmt 0)

It is important to separate the question "will outbound links decrease your PR?" from the question "will outbound links help you in the SERPs?"

Clearly linking out to pages that do not link to you does "leak" PR from your site. Pagerank is calculated as the eigenvalues of a link matrix, which can be thought of as equivalent to a "random surfer" model, in which you imagine a hypothetical surfer clicking on random links -- where the surfer spends the most time has the most PR. Linking out sends the random surfer to some other page.

However, this does not mean linking out is bad. There are many factors in the algo, PR is only one. Google has said before that it is easy to spot a "PR hog," that is, a site which refuses to link out and is designed to hoard PR. Normal sites link out where appropriate. It has been speculated that links out to relevant pages may increase the relevance of a page, but I don't think this is known.

The bottom line here is that Google can tell a lot about your site from its linking patterns, and Google wants "natural" linking patterns. Google can be expected to get better and better at detecting this. So if your strategy is long-term, you should link out where appropriate to your users, that is, provide on-topic outbound links whenever you feel like it. The best way to "simulate" a natural link pattern is to just do whatever makes sense from a user perspective, that is, don't simulate it at all.

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