Fowlkes-Mallows index

The Fowlkes-Mallows index measures how well two different clustering results (groupings) of data agree with each other. It compares pairs of items, checking if they are grouped together or apart in both clusterings. The index ranges from 0 to 1, where 1 means perfect agreement—both clusterings group items in the same way—while 0 indicates no similarity. This metric helps assess the consistency or stability of clustering methods, guiding improvements and comparisons in data analysis.