For a long time, keyword density has been taken very seriously in search engine optimisation. Keyword density, for those who aren’t familiar with the term, refers to the number of times that your primary keyword appears in the content of a given page. (The primary keyword being the word for which you’d like to appear in the search engine results.)
Although keyword density has been an important factor in the past, it has been argued that search engine algorithms have evolved significantly, and that keyword density no longer offers a useful measure of content relevance, and hasn’t done for some time.
Why Keyword Density Doesn’t Help
In his fascinating, if somewhat impenetrable, article, The Keyword Density of Non Sense, Dr. E Garcia explains why keyword density doesn’t provide a useful measure of relevance.
His main point is that, since the keyword density formula only determines the amount of times that a given phrase appears in text in relation to the total number of words or phrases, and cannot determine the distance of keywords from each other, the value of the intervening phrases, or the distribution of the keywords. As a result, the keyword density ratio is completely divorced from the content and context. Below, you can see the keyword density formula, which calculates the number of times a given phrase is repeated in relation to the total number of phrases or words.
Keyword Density = (Nkr / Tkn) x 100
Where Nkr = The number of times you repeated a specific keyword
And Tkn = Total number of words in the text
So, if your body of text is 500 words, and you’ve repeated a certain keyword 15 times, the calculation will look like this:
Keyword Density = (15 / 500) x 100
= 0.03 x 100
= 3% keyword density
In short, keyword density has no relation to the quality or relevance of the copy. He goes on to explain that the entire notion of keyword density actually predates the advent of commercial search engines as we know them, and that keyword density plays no role in how commercial search engines process text, index pages, or assign weights to terms.
According to Dr. Garcia, the sole reason that search engine optimisers still focus on keyword density as an important factor in optimisation is misinformation.
Search Engine Weighting Factors
* Search engines place significant weight on domain age, site authority, link anchor text and usage data.
* The page title is given more weight than other text.
* Hidden information like meta tags and comments are given less weight than page content.
* Page copy which is bold, linked, or in a heading tag is probably given greater weight than normal text.
* Weights assigned by search engines are relative. Putting all your copy in an H1 tag does not give it greater weight, and may give it less.
* Bolding H1 text will not give it greater weight.
Keyword Density Mistakes
Focusing too much on keyword density can have it’s own drawbacks. Here are some of the problems that tweaking your keyword density can potentially create:
* Because queries are often random, changing your copy to achieve a higher keyword density can actually cause you to lose some of the long tail keywords that are helping your page appear relevant.
* Advanced semantic algorithms may look at supporting vocabulary when determining relevance. A naturally optimised page should be able to convey its message, even if you remove the keyword phrase entirely.
* Focusing too much on keyword density can create content that people are not interested in reading, or linking to.
While it’s undeniably important to make sure that your keywords appear on your page, it’s equally important to ensure that they do so only so far as is relevant to your content and the overall message or theme of your page.
Writing content which conforms to an idealised notion of keyword density is neither effective, nor necessary. The message of your page should be clear, without having to resort to countless repetitions of your keyword to achieve it. And well written content should naturally optimise anyway, in an organic sense.