A Top-Level domain is the right-most part of your domain after the last dot. Common Top-Level domains (referred to as TLDs in the rest of this study) include ".com", ".net", ".org", and ".edu". There are also two letter TLDs for every country such as .ca for Canada, .us for United States, .au for Australia, and .uk for the United Kingdom.

Can your choice of a TLD affect your ranking on Yahoo and Google? Answering that question is the goal of this study.

The methodology used to find the answer is fairly simple. I gathered the results of the queries naturally performed last month by myself and three associates using Yahoo and Google. I then tallied the results for the first 10 rankings for several common TLDs on both Yahoo and Google (keeping the results separate). Many of the TLDs we tested were not present in the search results in a sufficient quantity to have statistically valid results. They were eliminated from the study.

Those results were further refined by converting the trend of rankings 1 through 10 into a normalized correlation. The final number was in the range of -100 to +100. A -100 would indicate that the number of occurances for each ranking would suggest that the pages with that TLD always ranked lower than other TLDs. A score of +100 would indicate that pages of with that TLD always ranked higher. Scores near zero would indicate that the results were randomly distributed for that TLD, so it was likely that pages of that TLD ranked about the same as other TLDs.

Here is the graph showing Google and Yahoo results:

The X-axis shows the various TLDs that made it through the study. The Y-axis shows the ranking correlation score. It should be noted that all four researchers are location in the United States. If the search engines use any kind ...