How to determine the quality of external links

Example 1: Suppose a Web site, the PR value of the link is 4, the number of external links to 10 of the site, the formula is as follows:

PR (A) = (1-0.85) + 0.85* (4/10) = 0.49. From this can be seen, if the site to obtain a PR value of 4, external links to 10 of the site's links, and finally the site will get a PR score of 0.49.

Example 2: If the site is a PR value of 8, the number of external links to 32 of the site link, then the site will get the PR score will be: PR (A) = (1-0.85) +0.85* (8/32) = 0.3625.

Thus, the PR value of the external link site is important, the number of external links to the site is also an important factor to consider. According to the analysis results can be drawn: in the construction of external links to the site, should try to find those PR value high and the number of external links and fewer sites. The more external link sites such as this site, the higher the PR value will be, the rankings will be significantly improved.

PR Value Calculation formula for page A: PR (a) = (1-d) + D (pr (T1) C (T1) + PR (T2)/C (T2) +...+ PR (TN)/C (TN)).

Among them: PR (Ti) indicates the PageRank value of the page T linked to A; C (TN) indicates the number of outbound links for the web page Tn; D is the damping factor, taking 0< D < 1, and Google usually takes a value of 0. 85. Note here: A website's voting rights are only 0.85 of the PR value of the site, and the 0.85 weight is evenly distributed to each of the external sites it links to.