Many SEOs claim that domain names containing your major keyword rank higher for that keyword. Others claim that the stem part of your URL – the part following the domain name – should contain the keyword that reflects the topic of the page. Since both of these theories can be easily tested through statistical analysis, we decided to tackle the pair this month.

We began by gathering the results of the queries performed last month using Yahoo and Google and analyzed them in respect to our first question: Does having your keyword in your root domain affect ranking?

After tabulating results for the first 8 rankings on both engines – while keeping the results separate – we converted them into a percentage of total results for each engine. Here's the graph showing results for both Yahoo and Google:

The X-axis (horizontal line) shows the ranking (from #1 through #8) of the search engine results in the study. The Y-axis (vertical line) shows the percentage of domains that contained the keyword used in each search.

Wow!  Both search engines do, in fact, rank pages with the keyword in the root URL higher on average. With Yahoo there was a 100% correlation — statistically speaking, a very rare event. That means there were no exceptions in the data points. Each higher ranking showed a higher percentage of sites using the keyword and vice-versa.

The Google result was also a very high correlation – revealing that 64% of the time the data points were in the proper order. And, by looking at the graph we can see that when they were "out of order" it wasn't by very much.

Usually, we'll caution that a statistical analysis