If a site is listed in 100 directory, what will be its pagerank

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.

but that’s not too helpful so let’s break it down into sections.

1. PR(Tn) - Each page has a notion of its own self-importance. That’s “PR(T1)” for the first page in the web all the way up to “PR(Tn)” for the last page
2. C(Tn) - Each page spreads its vote out evenly amongst all of it’s outgoing links. The count, or number, of outgoing links for page 1 is “C(T1)”, “C(Tn)” for page n, and so on for all pages.
3. PR(Tn)/C(Tn) - so if our page (page A) has a backlink from page “n” the share of the vote page A will get is “PR(Tn)/C(Tn)”
4. d(... - All these fractions of votes are added together but, to stop the other pages having too much influence, this total vote is “damped down” by multiplying it by 0.85 (the factor “d”)
5. (1 - d) - The (1 – d) bit at the beginning is a bit of probability math magic so the “sum of all web pages' PageRanks will be one”: it adds in the bit lost by the d(.... It also means that if a page has no links to it (no backlinks) even then it will still get a small PR of 0.15 (i.e. 1 – 0.85). (Aside: the Google paper says “the sum of all pages” but they mean the “the normalised sum” – otherwise known as “the average” to you and me.


BTW You can work out roughly what your PR will be although it's a difficult equation

 

It depends on the directories PR. If all the directories are PR 0 then you will probably have pr 1 if they are like PR 4 - 6 you will get higher PR.

- Prilep

 

If you ask this question to the creator of PR formula thay can answer you in about 3 days calculation , Please ask some easy question Bro
may be you get pr5 but submit to the pages where you find least links, its very important to get high PR, submission to a pr3 page which has 5 link is better then submission to pr5 page with 20 links. understand?

 

Hey hey --very good point- I don't think even the creator Larry Page can say this --as I think there were several programmers involved in creating the algo.

I can't support this formula bro. A PR5 link with even 50 OBLs is more valuable than a PR3 link. May be you don't get as much PR juice as the PR page with 10 OBL will give but it is still either equal to PR4 or better.

 

How about the middle ground. Someone worked out a while ago that each jump in page rank needed 5 times as many links as the lower level. So on average a link on a PR5 page with 50 links on is the same as a link from a PR4 page with 10 links on or a PR3 page with 2 links.

Sounds possible to me, but like you say we'll never really know.

 

Actually that equation is very simple (additions,multiplications,...)
What is difficult is to run that "simple" algorithm on a huge graph (a graph is a set of nodes interconnected by arcs) of billion pages (nodes) interlinked by billions of links (arcs).

Take this ridiculously simple example:
the whole web consists of only two pages, Page A, which google trusts very much and assigns to it a PR of 10, and another page B which google doesn't know yet, they are busy working on page A
A and B did a link exchange
Algorithm
Initialization: A=10, B=0
Step 1: Google finds the link from A to B then A share its PR with B A=5, B=5
Step 2: G finds a link from B to A => A=7.5 B=2.5
Step 3: G recrawls A find the link to B again => A=3.75 B=6.25
Step 4: A=6.875 B=3.125
and so on....
The algorithm may never converge unless they specify a condition to terminate it.
See how it is complicated with this 2 pages web? how about billions of them.


This description here is just my understanding of how the PR algo works. how PR is shared or passed between pages is google's secret.