PR - How the hell it's calculated?

[wasistdas]

I dont complain but it is very very very funny thing. On of my websites (quite old though - 3 years) has not many visitors per day, around 10 or so. But Google PR is 5. Some others of my website with more visitors have only PR3 and 4. I'm a lil confused how actually PR is calculated. Anyone knows?

 

[tajimd]

Your old site might have more backlinks. The number of visitor does not counts for PR. The more number of backlinks....the more will be ur PR.


Quoting from the original Google paper, PageRank is defined like this:

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.

To calculate the PageRank for a page, all of its inbound links are taken into account. These are links from within the site and links from outside the site.

PR(A) = (1-d) + d(PR(t1)/C(t1) + ... + PR(tn)/C(tn))

That's the equation that calculates a page's PageRank. It's the original one that was published when PageRank was being developed, and it is probable that Google uses a variation of it but they aren't telling us what it is. It doesn't matter though, as this equation is good enough.

In the equation 't1 - tn' are pages linking to page A, 'C' is the number of outbound links that a page has and 'd' is a damping factor, usually set to 0.85.

We can think of it in a simpler way:-

A page's PageRank = 0.15 + 0.85 * (a "share" of the PageRank of every page that links to it)

"share" = the linking page's PageRank divided by the number of outbound links on the page.

A page "votes" an amount of PageRank onto each page that it links to. The amount of PageRank that it has to vote with is a little less than its own PageRank value (its own value * 0.85). This value is shared equally between all the pages that it links to.

 

[mole]

Thanks for the information post, taj. I have a couple of pure parking pages with a PR of 5, wonder how that happened?

 

[peter phillips]

I would suggest you to refer to the following links for more information regarding PR and PR algorithm

http://en.wikipedia.org/wiki/PageRank
http://www.iprcom.com/papers/pagerank/

 

[romow]

check with google/yahoo/msn to see if they have any backlink.

Thanks for the information post, taj. I have a couple of pure parking pages with a PR of 5, wonder how that happened?

 

[wasistdas]

Well, my site has 700+ backlinks. Hmmm, I did nothing but a couple of directory entries back in 2002

 

[tajimd]

Yes , if u had used automatic linking service then your back link keeps on incresing . but those automatic backlinks does not effects your ranking that much . It is the one way solid link which google requires for PR increase.