Keyword clustering options
SOFT
The Clustering tool finds the most popular keyword and compares the TOP-10 search results displayed for this keyword with the TOP-10 results displayed for the other keywords by the number of matching URLs. If the number of these URLs matches the selected grouping level, the keywords are banded up together. All keyword within a group are related to the most popular keyword, but they are not necessarily related to each other (will not necessarily have matching URLs).
MODERATE
The Clustering tool finds the most popular keyword and compares the TOP‑10 search results displayed for this keyword with the TOP‑10 results displayed for the other keywords by the number of matching URLs. At the same time, it compares all keywords with each other. If the number of these URLs matches the selected grouping level, the keywords are banded up together. Each keyword within a group will have a related keyword with matching URLs. But two different pairs of keywords will not necessarily have matching URLs.
HARD
The Clustering tool finds the most popular keyword and compares the TOP‑10 search results displayed for this keyword with the TOP‑10 results displayed for the other keywords by the number of matching URLs. At the same time, it compares all keywords to each other and all matching URLs in the related pairs. If the number of these URLs matches the selected grouping level, the keywords are banded up together. All keywords within a group will be related to each other and will have the same matching URLs.