September 28, 2007

How to calculate Page Rank

Page Rank is a measure of the popularity of a web page. More pages link one page, this page will have a bigger Page Rank.

It is very useful for us, webmasters, to know the value of Page Rank that our page receives from pages that link it. To have this information, we need data for each page that links to our page: the real value of Page Rank and the total numbers of links on the page.

The value of Page Rank that we know is those that we can read from Google’s Toolbar. That value is a logarithmic representation of the real value. I will assume that the base of logarithm is 7 (the real value isn’t known).

The formula that is used to calculate the real value of Page Rank that one page (lets call it page A) passes to another page (lets call it page X) is:

PR[Xa] = d * ( PR[A] / C[A])

With words: the Page Rank that the page X receive from the page A (PR[Xa]) is obtained dividing the real Page Rank value of the page A (PR[A]) by total number of links on this page (C[A]) and multiplying by dumping factor (d). I will assume that the value of dumping factor is 0,75 (the real value isn’t known).

The total value of Page Rank of page X is the sum of all contributions that the page receives from the pages that link it. For example, if the page X is linked by pages A, B, C and D, the real value of Page Rank will be:

PR[X] = PR[Xa] + PR[Xb] + PR[Xc] + PR[Xd]

Using this information, we can produce a table with ranges of real values of Page Rank that one page (A), with a certain Page Rank, read from Google’s Toolbar, gives to an another page (X), supposing that on the page A there is only one link, to page X.

PR Minimum Maximum
toolbar Value Value
0 1 4
1 5 36
2 37 256
3 257 1.800
4 1.801 12.604
5 12.605 88.236
6 88.237 617.656

Attention: there are not real values of Page Rank, but real values passed from one page to another.

The minimum values are obtained raising number 7 (base of logarithm) to the PR power and multiplying by 0,75 (dumping factor), for example: the minimum value of Toolbar’s Page Rank 5 is (7^5)*0,75 = 12.605.

The maximum values are obtained simply by decrementing by one the minimum value of the superior Page Rank, for example: the maximum value of Toolbar’s Page Rank 5 is 88.237-1 = 88.236.

Now, to have real value that one page pass to our page, we must take the real value of Page Rank of that page from the table and divide it by total number of links, present on the same page. Here is the problem. What value to take from the table: the minimum or the maximum one, or an average?

It’s impossible to resolve this problem because we don’t know exact value of Page Rank, but only an interval of values. Personally, I always work with minimum value so, in this mode, I’m sure that my calculations are underestimated.

An another problem to resolve is how to find the number of links on the page that we examine? There are Internet sites that offer free tools with which we can obtain this information.

At the end of all calculations, summing Page Ranks that we receive from any page that link our page, we have a real value of Page Rank of our page. Lets suppose that this value is 780. To get an equivalent Toolbar’s Page Rank, we have to calculate logarithm to base 7 of this value. Normal calculators have not this function, so we can calculate it using logarithm on base 10, in this mode: log(780) / log(7) = 3,4. Toolbar’s Page Rank is always represented as an integer number, simply ignoring the decimal part of result, so Toolbar’s Page Rank will be 3.

September 17, 2007

Introduction with the opening of this blog for Webmasters

There is no need to try to explain the importance of Google’s Page Rank. Every webmaster knows that the best internet traffic comes from search engines, and Google, in this moment, is the most important. So, the main task for a webmaster is to get his site placed as high as possible in Google search results.

Everybody also know that to be placed in first positions the page must be well written, with the selected keyword well spreads in the titles and in the text of the body, that the page must have a lot of incoming links (the link that link the page from other sites/pages), that those incoming link must use the selected keyword as link text, and that the page must have a good Page Rank.

It seems to me that many webmasters do not fully understand the concept of Page Rank and how to obtain it. In this blog I will try to address some of the arguments that I frequently discussed with other webmasters in order to express my opinion regarding this issue.

I used this introduction to tell immediately on, due to me, very important fact. All webmasters that work hardly to place their sites at the firsts positions of searching results, base their efforts using information that have and that often are not very reliable, and coming from different fonts.

Google doesn’t give much referent points, and frequently those points can be interpreted in different ways. Google recommends to webmasters to make sites for surfers, not for SE placement, and to look own sites with the critical eye of visitors, to understand better the quality and the potential of them. You must ask yourself: “Will my visitors find those they are looking for”? I recommend the same thing in the different way, to look the site white the eyes of Google, and to ask yourself: “If I were Google, what should I think about my site”?