How are keyword clusters created?
Using the SERP clustering method, keywords are grouped based on the percentage of URLs they share in the top 10 search results with the main keyword, the keyword with the highest search volume in the cluster.
This method requires having the SERP extracted for the keywords.
To be grouped, keywords must have at least a 40% overlap in their URLs (default threshold).
When you click on the cluster title, you'll see a list of the keywords included in that cluster and a percentage sign indicating the similarity of their top 10 search engine results pages (SERPs) with the main keyword.
Clustering is done using live search results data, so you can be confident that you're getting the most up-to-date insights.
PS: It's possible to adjust the percentage of URL overlap required for keywords to be included in the same cluster (see settings), as well as the number of search results to take into account.