We recently decided to invest a (sizeable) sum of money into subscribing to Keyword Discovery. It seemed as though it would be easy to use, with an export facility to help present results to our clients as well as boasting an extensive data set based on “keyword search statistics from over 200 search engines worldwide”. You would assume that with such a large database you would be able to get a fairly accurate idea of what key phrases people are really searching on.

Previously, we had been using Free Keywords which is a free piece of software that you can download to your desktop. This tool takes its data from the Overture database.

Both keyword selection tools are different in terms of the where and over what time period the data is collected from. I carried out a few test searches and compared data from both tools to see what kind of difference there is between the number of searches reported in Keyword Discovery and Overture for the same search phrases.

Test One - Niche:

Due to the fact that the data from Overture is for the last 30 days and the data from Keyword Discovery is from the last 365 days, the OV figures have been multiplied by 12 to allow a fairer comparison.

Test Two: Competitive:

As you can see, there is a huge difference in the results returned between the two tools. How can this be explained and which tool is more accurate?

Three of the main differences in the data used for these two keyword research tools are as follows:

1).        Time period. Although I have tried to take this into account by rationalising the data, a simple multiplication by 12 does not consider other factors such as seasonal changes. Exam papers for instance are likely to popular searches during mock exam period but not over the summer.

2).        Both tools have different “data cleansing” techniques. For instance, Overture de-pluralises, de punctuates, etc.

3).        Both KD and OV gather their data from very different sources – OV is based on searches made across the Yahoo network, whereas Keyword Discovery is made up of searches carried out on over 200 search engines worldwide.
Neither of these is right or wrong, but both have inherent flaws to their model. Overture for example, is prone to inflated results due to skewing by automated rank checkers. Overture would also count, for example, the following terms as the same term:

Online website marketing
Website marketing online
Marketing website online

The best solution to nailing a reasonably accurate and relevant keyword list to work from is to review a range of keyword research sources and then devise a set of algorithms to apply when combining the data.

Another option might be to run a PPC (pay per click) campaign for a week or two to gather data about the number of impressions you get for keywords you are testing.