SEO Israel » Google » Pagerank Calculation
How is the PageRank calculated?
The connection between the PageRank and Google's toolbar information
Losing PR as a result of linking to another page
PR determining cycles
PR maximizing strategy
One of the most important topics that webmasters need to understand is the way PageRank is calculated. However, this subject is not simple, and requires some understanding in this field..
A pagerank is a numerical index that is used by the Google search engine in order to measure the importance of a certain webpage. Google measures This by checking for the number and quality of the page's incoming links. Every direction to a webpage serves as a "vote of confidence" for that page, and the higher the number and quality of incoming links, the higher its importance will probably be.
A number of things that you should know about PageRank:
Pagerank is assigned per page and not per site.
I will be referring to the Pagerank term in its abbreviated form - PR.
Although there is no certain way to know how Google calculates the Pagerank, it is possible to assume that the calculation method remained similar to the last method on which certified information is available.
Google uses the next formula for calculating pagerank:
PR(A) = (1-d) + d(PR(t1)/C(t1) + ... + PR(tn)/C(tn))
This is the point at which most people who read articles on this topic despair ? if you are still interested to continue reading, lets take a deep breath?
The various parameters in the above equation are:
PR - PageRank
Actually, if we observe the equation, we can understand a few things:
A page's PR = 0.15 + 0.85 + (the total of transferred votes of confidence).
The above equation will yield a result between 0.15 and infinity. So why is it that when we check the PR displayed on the Google toolbar, we receive a number that is between 1 and 10?
After assigning the final score using the above formula, Google divides the webpages into ten groups (PR1-PR10). The size of each group varies! The size decreases exponentially: there will more PR3 than PR4 webpages, and more PR4 than PR5 webpages. Progressing from PR to PR is harder for higher PRs.
When a webpage votes for another webpage, it does not lose PR. The PR level is not set by the pages it votes for, but rather by the pages that vote for it. However, when a page votes for a webpage on another site, it creates PR Leakage, meaning that the PR that could have been added to other pages on the same site are instead invested in pages on a different site.
Every time a webpage's PR is calculated, the new value affects all the pages this webpage links to. But what happens if one of these pages links back to the original page? If I give a vote of confidence for someone, and he votes for me in return, then we will be strengthening each other infinitely. It turns out that after a number of mutual voting cycles, the value of both sides eventually stabilizes. In each calculation cycle, a more exact value for the two pages is achieved, until eventually the value is close enough to say that the error is negligible.
When you know how the PR works, you can plan a correct links structure in order to maximize the PR in the right places on your site. For further reading on this subject, please refer to the Pagerank Optimization strategies article.
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