One of the more fascinating examples of smoke and mirrors in SEO is the idea of a formula to decide how often a keyword or phrase should be repeated within a page to increase the page’s relevancy to that word or phrase.
Documentation about information retrieval (the discipline that explain how search engines work) shows that the formulas used by search engines to calculate the relevancy between keywords and documents are far more complex than those invented by SEOs.
The use of artificial formulas by SEOs, for example the crude calculation known as ‘keyword density’, is wide spread in the SEO world. This is because SEOs wanted to industrialize the process of content optimization. Formulas also provide a pseudo-scientific touch, even if there is nothing particularly scientific about it.
SEOs would not be able to work with the same formulas actually used by the search engines, since they use parameters which are determined by data only the search engines have.
When writing content, it is best to use copywriting techniques, rather than insignificant arithmetic formulas. For example, including in the text the keyword and phrase you wish to rank for, without repeating to the point of making the text unreadable to the user.
This post is the English translation of a chapter of the italian ebook “Mitologia SEO” written by Enrico Altavilla.