I've seen another of subpages on websites that have PR3 or higher that have no inbound links except from their own menu structures but instead have lots of outbound links. The theory is that google allocated a Page Ranking of 1 to each page and any inbound links adds pr and any outbound links reduce pr. Given that how come there are so many link pages out their with high PR? My theory is its related to the domain age. Whats every one else theory?
Outgoing links do NOT reduce a page's PageRank. They absolutely do not! On top of that, putting links that point to high-quality pages MASSIVELY boosts the search engine performance of a page. This has been experimentally determined - I strongly recommend you read the results of this very serious study (not mine, FYI): http://www.webcredible.co.uk/user-friendly-resources/search-engine-optimisation/number-links.shtml High-quality outbound links have been part of my SEO strategy for a long time, and with excellent success. No, it does not hurt your traffic, but Google LOVES it. That's a win-win deal, if I ever saw one
I've read the same info from various SEO experts. Search engines like it when you link to high quality, and highly relevant, sites and webpages.
My theory is that a URL's PR is based SOLELY on it's inbound links. A URL's outbound links don't affect it's PR (except in the situation where Google catches you linking to a bad site or selling links in which case your URL's PR will likely be stripped so that it passes no PR to it's outbound links). Outbound links can affect other ranking factors such as domain trust that are also used a ranking factor for a URL, but outbound links do NOT affect the URL's PR. Well, that's not exactly theory... It's based on Sergey Brin and Larry Page's blueprint for Google that they wrote at Stanford called The Anatomy of a Large-Scale Hypertextual Web Search Engine (section 2) where they first described "Page Rank" as well as their US Patent on Page Rank. You can find a decent summary of Page Rank on Wikipedia as well. Once you read and understand the formulas, you can see it is simply a measure of link popularity - the number of followed inbound links to the URL and the strength of each of those inbound links. The amount of PR passed out from a URL on a followed outbound link is approximately PR(URL)/number of followed outbound links. I say 'approximately' because there is a damping factor that causes the total PR to decay as it is passed from URL to URL to URL ad infinitim. The formulas have likely been tweaked slightly over the years to handle things like rel="nofollow", but in general it still works pretty the same as described in the documents above.
An excerpt from the Article you quoted 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. The bottom line here is that if the sum of all webpages' pagerank is one then sure for any webpage to increase pr has to be at the expense of webpages that have lost pr which I presume can only be from outbound links which transfer link juice to pages with inbound links!
You don't take PR away from pages by having outbound links. However, you can diminish the amount of PR that one page is passing to individual pages by having too many outward links. This is the theory behind pagerank sculpting - using nofollow on internal links to pages that aren't important to you (contact pages etc), so that the PR passing from your Home Page is 'concentrated' onto the ones that you want to benefit from it. Outbound links to not improve PR or serps per se. However, linking to established and authoratitive sites in your niche does add up to an overall impression of your site as being a 'real' site, of use to visitors, and part of the wider internet community, which is the sort of site that Google likes.
Are you saying that you pass PR through internal links but not external but with the amount of external links passing PR to other sites but not losing PR on the sites they came from, then the sum of PR of all webpages must be greater than 1 which is contrary to what google is saying?
An excerpt from Sergey Brin and Larry Page's blueprint for Google http://infolab.stanford.edu/~backrub/google.html "Note that the PageRanks form a probability distribution over web pages, so the sum of all web pages’ PageRanks will be one." What does this mean?
Not necessarily... Linking from your URL to just any average site will generally NOT help you. But linking to certain types of sites can. Google has 200+ ranking factors that they are looking at each time they rank a URL for a particular keyword phrase. One of these ranking factors is called "domain trust". You can increase your domain's trust rank by getting links from trusted sites AND by linking to trusted sites. Check out this SEOmoz Video on Domain Trust and Domain Authority if you don't understand how it works.
The "one" they are talking about is 1.00 or 100% probability just like the damping factor they talk about is 0.15 or 15%. The whole theory around Page Rank is based on probability. If you'll recall from the whitepaper: Not being a statistician myself, I take it as meaning the higher a URL's PR, the more likely a random visitor will visit the page which makes sense if you think about it. A PR8 site is going to have MANY more inbound links than a PR1 site. It will likely have more links from higher PR sites as well. The probability that a web surfer will stumble onto that PR8 URL by following a link while surfing the web is much higher than the probability that they will stumble onto the PR1 site if for no other reason... because there are more links to that page and/or links from other sites that themselves are high PR and have lots of inbound links. But it was the formula that I was trying to get you to understand in my original post which basically shows that PR of a URL is the sum of the various PRs passed into it on each of its inbound links. And to calculate how much PR is being passed into the URL A from URL B, they basically divide the PR(URL B) by the number of followed outbound links from URL B. They take into account the dampen factor. They repeat this for each inbound link to URL A and then sum them all up to get the PR of URL A.
The PageRank system is a numerical grade from 0-10. There have been great articles written in the past on how to estimate and compute PageRank, and they can be confusing to some. So, in a simplistic breakdown, think of PageRank in terms of point value. The following numbers are not valid; they are just used to visualize the process: PageRank Value 4 -10 5 -100 6 -1,000 From this example, the values increase by ten fold for each level of PageRank. This is very similar to how it actually is. It is approximately ten times more difficult to climb to the next "rung" in the PageRank ladder.
When determining value of a link, you must go to the page where your link will be present. If that page has a PageRank of 5, write down "100". This is the "value" of the page. The value of that page is then shared with every link on the page including any graphics that serve as links (i.e. banners). Count up the number of links on the page. If there are 20 links, you divide 100 by 20 to get a value of 5 per link. If it takes 1,000 points to reach a PageRank of 6, you would need 200 of these types of links to achieve that level. However, had that page been a PageRank of 5 but with the number of links being 10, instead of 20, each link would be worth 10 points instead of 5. It would take just 100 of these links to achieve a PageRank of 6 instead of 200. See the difference? It is called quality. This is why link farms, web rings, etc. are worthless. The PageRank value becomes diluted. Also, participating in these types of programs does not benefit the web community; they are done for no other means than artificially inflating your PageRank.
Thanks canonical for highlighting the video which was pretty interesting. However, I can't help but think there are alot more things that we think google does than it actually does. Afterall, how complicated can it get to manage millions of websites and return results quickly!
Can anyone explain how the sum of all web pages Page Ranks will be one if outbound links give PR juice but don't lose any?