Link Value Calculation and Search Engines

As discussed in the articles on SEO, aside from the actual content of your site, your search engine position will be determined almost entirely by the number and quality of incoming links (links from other sites to your site). A common mistake is to focus on quantity rather than quality, but one should be aware that a single high-quality link can contribute more to your search engine position than 100s of low quality links.

It is possible to calculate the value of an incoming link, and thereby have a guide to how useful it is to improving your search engine position. Immediately below is a form for calculating the approximate (indicative) value of an incoming link. Underneath is the detailed explanation and caveats.

Page Rank	Page Rank 01 Page Rank 02 Page Rank 03 Page Rank 04 Page Rank 05 Page Rank 06 Page Rank 07 Page Rank 08 Page Rank 09 Page Rank 10
Link Text	Keywords not included Includes keywords Exact keyword match
Relevance	Meta Title Meta Description Text URL
Number outgoing links	Over 50 links 20 to 50 links 5 to 20 links 2 to 5 links Only links to my website
Page content	Links within paragraph Content rich page
Link issues	No Follow Link Invisible page Dynamic page Reciprocal link Paid Link or Link Farm

Evaluating the results

The above form gives a number, which is an indication of the value of the link. The higher the number, the more valuable the link. The value is linear, so if you are comparing links from two sites and one link has a value twice that of the other link, it is 2 times as valuable.

If you complete the above form and get a link value of '1', this indicates an extremely basic link (e.g. from an unimportant page, which has limited and unrelated content). A value of 50 or above is an indication of the beginning of a quality link; although such links on their own are unlikely to make much difference to your search engine position, a substantial number of such links can in combination may. A value of above 1000 indicates a link of substantial value.

Explanation of the fields

Following is a brief explanation of each of the fields above. Please note that calculations are approximate, as discussed in Caveats below.

• Page Importance. A link from a highly respected site (or more accurately, highly respected page) is worth far more than one which isn't well respected. To use an analogy, if you are going for a job interview then a recommendation from your ex-boss is worth a lot more than one from your brother. Likewise, a link from a major website (e.g. a national newspaper) is worth more than from a minor website. The quickest way to get an approximate indication of the importance of a page is to use its PageRank. If you have Google toolbars installed on your browser, this will appear each time you navigate to a site. If you do not, you can use one of the online tools (such as PageRank Calculator) to determine the pagerank. Each increase in PageRank increases the value of a link from that page by a factor of approximately 5. In other words, a PR3 is worth 5 times as much as a PR2, a PR2 is worth 5 times as much as a PR1, a PR1 is worth 5 times as much as a PR0. This means that a PR3 is worth 125 times (5 * 5 * 5) as a PR0.

• Link Text. If you want to rank well for your keywords (keyword phrases), you should ensure the link text for incoming links matches your keyword phrases. It is probably best if you don't use the identical link text for all incoming links (this can trigger a filter in the search engines) but strive for the important links to include your link keywords.

• Relevance. If the page linking to you is related to your website topic and keywords, the link is is far more importance. To use an analogy, if you are looking for a new dentist, you are probably more likely to trust the recommendation of your local doctor than that of your local plumber. Likewise, if you are selling furniture, a link from another furniture page will be of more value than a link from a page about automobiles. Search engines use a number of criteria to determine relevance. In particular, do the meta tags (META TITLE and META DESCRIPTION) contain your keywords, does the page text contain your keywords and does the page address (URL) contain your keywords.

• Number Outgoing Links. If a page has a large number of outgoing links, the importance of the page is diluted by the number. For example, a link from a page with only 3 outgoing links is worth for more than a link from a page with 50 outgoing links. This is partly due to the fact that search engines consider pages with many outgoing links are considered to be less discriminating in terms of linking than pages with few outgoing links.

• Link Location. Some websites group all their outgoing links together, typically at the bottom of the page. Search engines tend to see such links as less important than links within a paragraph. Likewise, links from a page which is largely empty of content are less valuable than links from a page with a large amount of content (e.g. text).

• Link Issues. Some webmasters hide outgoing links from the search engines, so that they appear to have many incoming links but few outgoing links. In this case, the link to your site may be worthless. Check if the link to your site has a 'no follow' attribute hidden in the code. Also check if the page itself is hidden (any page with a PR over 0 is visible, pages with a PR of 0 may or may not be hidden). Static pages are usually more valuable than dynamic pages, not least due to the fact that multiple dynamic pages can be combined into a single page from the perspective of search engines. Due to the excessive use of link exchanges, 'reciprocal links' are valued much less than 1-way links.

Caveats

One should keep in mind that the above information and calculation is approximate only, due to a number of variables:

• Google, Yahoo, MSN and other search engines have a number of different ways of calculating link quality. Due to the different weighting they give to each factor, the calculation for each is somewhat different for each search engine. That being said, all the major search engines use approximately the same approach.

• The way in which search engines calculate 'link quality' varies over time, in part due to their efforts to identify and eliminate Black Hat SEO. Fortunately, if one follows the basic principles outlined below, this should not be a major issue.

• The exact formula for calculating link quality is a closely-held secret, mainly in an attempt to limit Black Hat SEO. However, Google and others have released the basic formula (the major factors, along with an indication of their relative importance). SEO experts have then used cross-website studies to refine this, resulting in a good approximation of the formula actually used.

• For a number of variables, the exact effect depends on circumstances. For example, the use of a dynamic page rather than a static page will almost certainly decrease the value of a link. However, the extent to which the link value is reduced will depend on exactly how the dynamic page is used within the context of the website. As the purpose of this tool is to give a quick indicative value, we have assigned typical (averaged) values to the various variables rather than achieve greater precision at the cost of greatly increased complexity.

Consequently, while we make no claims that the above information is either complete or precise, we feel that it provides a reasonable indication. If you have any comments on it, please Contact Us.