Critical Analysis of Google PageRank Dissemination
Date Added: March 17, 2009
Author: Jessica Navarro
In the SEO arena there is a lot of focus on PageRank as an indicator of a domain’s SEO value. Although it is probably one of the most important aspects of a domain’s worth in the eyes of Google, there are a few details that should be understood.
Google gives each page on the web a score and when one page links to another it passes some value onto the page it is linking to. To begin with, for anybody who doesn’t know what PageRank is – it is a metric used by Google to decide how important a domain is based on analysis of link on the internet. The higher the PageRank, the more likely Google is to trust it. Google PageRank has eleven values, between 1 and 10. Pages that don’t have any PageRank are often referred to as having N/A PageRank.This is true for both external and internal links.
The most important factor in the assignment of PageRank to a web page is the PageRank of the web pages linking to it. Sheer quantity of links does not help to increase PageRank. Also, web pages that have a lot of low PageRank and PageRank N/A hyperlinks pointing to them can have their PageRank lowered as a result. A website can have a high PageRank with relatively few links pointing to it if those links are of a high PageRank.So, if a page has 4 PageRank 4 and 3 PageRank 3 links pointing at it, it will probably be give a PageRank of 4. The higher the PageRank of pages linking to a given page, the higher its PageRank is likely to be. PageRank is generally not assigned to a web page higher than the pages that link to it.
There are those that suggest that the text content of the page affects PageRank assignment, but this doesn’t seem to be the case. There is no substantiated evidence that text affects PageRank other than pages that have been spammed often have their PageRank removed.
When it come to sub-pages, the time Google has known about them is a factor in PageRank assignment. When new sites first get given PageRank their sub-pages often remain without any PageRank. In general, sub-pages are a little slow to get assigned PageRank. Google is generally less trusting of sub-pages unless they belong to a trusted domain. In particular websites with a lot of sub-pages and even more so sites that link to a lot of internal pages (like directories) can really struggle to pass their PageRank to internal pages.
The structure of the site has a major role to play in the assignment of PageRank. Google uses what is known as block level analysis to analyses web pages. They use their vast knowledge of the nature of the web to decide what links on a page are probably the most important and the pages these links point to are more likely to be assigned PageRank.
Google can and do manipulate websites’ PageRank. This is generally as a penalty for sites that have used unhonest methods. This can often cause all the site’s sub-pages to loose their PageRank. It has also been claimed that in the past Google has made mistakes in PageRank distribution.
Finally, the PageRank of a web page may change even when there has been no change in the links pointing to that page. This is either due to changes in the structure of links between all websites or modifications made by Google.
Sky Alfaro is an SEO consultant with the SEM Labs SEO Agency where she helps small to medium sized companies with search engine marketing training.