How quality of links might be computed
- SEO |
I have compiled my knowledge about how link quality might be computed and put them in a post here. I hope someone can find this article useful as a wage to my writing 
How quality of links might be computed
When the search engine robots reach a link on a page, several parameters are recorded for more inspections. Below is the parameters which I believe search engines will extract before evaluating the link quality.
- Anchor Text
- Position of the link
- Is the link "nofollow"?
- Is the link part of web site's template or design?
- Page rank of the link page.
- Total number of Outbound links on the linking page
- Link age
- Linking page age
- Linking domain age
- Texts before and after the link.
- Is the Anchor Text a keyword? If so, how many words is it and what competition is in that keyword(s).
After the data is collected, search engines will examine them for evaluating link quality. The process to be done is more complex and is much dependant to the search engine's algorithms which is kept secret to public. These algorithms are continually changing and improving and you will experiment these situations when looking at the search engine results fluctuating (not all fluctuation is an algorithm update)
Google might use following factors for link quality evaluation:
- Relevancy of the anchor text to the context of the linked page. Less relevancy means less link quality value. In some cases this value can be zero (in that case, there is no difference between having a link on that page and not having a link)
- Relevancy of the linking site to the context of the linked site. Experiments show that this factor is less importance than the above factor.
- Position of the link: Closer the link to the Body tag (or top of the page), the more value is added to the link quality.
- nofollow: If a link is nofollow, search engines might evaluate link quality as zero or near the zero.
- If a link is part of template or web design so that it is replicated in all pages with the same anchor text and exactly or closely in the same position, the link might have less value.
- Page Rank (PR) of the linking page is so important. Page Ranks are part of page's properties and are different than the main page PR.
- Total number of outbound links on the linking page is an important factor for evaluating link quality. Outbound links are the links leaving out a page. Links in a less clutter page, are more powerful than the links on link farm pages. As a rule of thumb, double the links on a page, will half the link quality. Google and major other search engines might filters the links except the first 100 links on a page.
- Link Age is one of the most important factors in link quality evaluation. Older a link, the more power is added to the backlink. Link Age, Page Age, And Domain Age, are three factors that Google, Yahoo, and Bing might utilize to suppress spammers from spamming search engine results. Age factor is a powerful tools in search engine's hands to clean search results from spamming. Spammers no longer are able to setup an own new networks of web sites and increase link popularity. But as getting the networks of web sites older, the power might comes to play.
- Texts before and after the anchor text are analysed carefully. These texts should be co-citation and relevant as they are relevant to the anchor text. The reason behind this analysis is to find farm link pages. Outbound Links to external sites on a page should be relevant in context otherwise search engine's spam filter might be trigged. In addition, texts before and after the anchor text are analysed for finding suspicious words and keywords such as "ad", "advertise", "advertisement", "sponsor", "sell page rank", "buy page rank" and etc. If suspicious words found, the texts are passed for more analysis for judging about selling backlinks and page rank.
- Type of the anchor texts are analysed carefully to determine if the anchor text is a keyword, phrase or seudo phrase. The type of anchor text might influence all above factors and the way link quality is computed. Links using keywords, might have different impact on link quality evaluation than the links using none keywords phrases. For example age factor in links using none keywords as an anchor text, might have less influence in link quality evaluation than the links using competitive keywords as an anchor text.
Hope I didn't forget something. If I did, I will come back and fix it.
How quality of links might be computed
When the search engine robots reach a link on a page, several parameters are recorded for more inspections. Below is the parameters which I believe search engines will extract before evaluating the link quality.
- Anchor Text
- Position of the link
- Is the link "nofollow"?
- Is the link part of web site's template or design?
- Page rank of the link page.
- Total number of Outbound links on the linking page
- Link age
- Linking page age
- Linking domain age
- Texts before and after the link.
- Is the Anchor Text a keyword? If so, how many words is it and what competition is in that keyword(s).
After the data is collected, search engines will examine them for evaluating link quality. The process to be done is more complex and is much dependant to the search engine's algorithms which is kept secret to public. These algorithms are continually changing and improving and you will experiment these situations when looking at the search engine results fluctuating (not all fluctuation is an algorithm update)
Google might use following factors for link quality evaluation:
- Relevancy of the anchor text to the context of the linked page. Less relevancy means less link quality value. In some cases this value can be zero (in that case, there is no difference between having a link on that page and not having a link)
- Relevancy of the linking site to the context of the linked site. Experiments show that this factor is less importance than the above factor.
- Position of the link: Closer the link to the Body tag (or top of the page), the more value is added to the link quality.
- nofollow: If a link is nofollow, search engines might evaluate link quality as zero or near the zero.
- If a link is part of template or web design so that it is replicated in all pages with the same anchor text and exactly or closely in the same position, the link might have less value.
- Page Rank (PR) of the linking page is so important. Page Ranks are part of page's properties and are different than the main page PR.
- Total number of outbound links on the linking page is an important factor for evaluating link quality. Outbound links are the links leaving out a page. Links in a less clutter page, are more powerful than the links on link farm pages. As a rule of thumb, double the links on a page, will half the link quality. Google and major other search engines might filters the links except the first 100 links on a page.
- Link Age is one of the most important factors in link quality evaluation. Older a link, the more power is added to the backlink. Link Age, Page Age, And Domain Age, are three factors that Google, Yahoo, and Bing might utilize to suppress spammers from spamming search engine results. Age factor is a powerful tools in search engine's hands to clean search results from spamming. Spammers no longer are able to setup an own new networks of web sites and increase link popularity. But as getting the networks of web sites older, the power might comes to play.
- Texts before and after the anchor text are analysed carefully. These texts should be co-citation and relevant as they are relevant to the anchor text. The reason behind this analysis is to find farm link pages. Outbound Links to external sites on a page should be relevant in context otherwise search engine's spam filter might be trigged. In addition, texts before and after the anchor text are analysed for finding suspicious words and keywords such as "ad", "advertise", "advertisement", "sponsor", "sell page rank", "buy page rank" and etc. If suspicious words found, the texts are passed for more analysis for judging about selling backlinks and page rank.
- Type of the anchor texts are analysed carefully to determine if the anchor text is a keyword, phrase or seudo phrase. The type of anchor text might influence all above factors and the way link quality is computed. Links using keywords, might have different impact on link quality evaluation than the links using none keywords phrases. For example age factor in links using none keywords as an anchor text, might have less influence in link quality evaluation than the links using competitive keywords as an anchor text.
Hope I didn't forget something. If I did, I will come back and fix it.