When running the Cluster mass operation in Relativity you'll see an option labeled, 'Create Cluster Score Field'.
If this box is checked off, the Analytics engine will generate a field which will show each document object's coherence score for a given cluster. This score shows a document's coherence score within the cluster. The coherence score used in the field tree for a cluster indicates how conceptually similar all of the documents in a cluster are. The document object cluster coherence score shows how far the document is from the middle of the cluster.
A coherence score will be some value between 0.0 and 1.0, with 1.0 indicating the greatest possible similarity, and a score of 0.0 for the lowest end of coherence for a cluster.
The cluster score field will be named in this format, 'Cluster :: [ClusterName] :: Score'. So in this below example we can see a set of documents which have scores of between 0.0 and 1.0 in the field named, 'Cluster :: custodians :: Score'. The document, AZIPPER_0007291 is in the cluster named, '02 gas, spread, heat, charts' and then down in the subcluster, '2.2 energy, power, trading, curve' and the sub-subcluster, '2.2.1 energy, curve, futures, nat ', and it has a score of 0.64, indicating how well it represents the cluster's overall concept. The coherence score for the cluster is 0.53 which shows how conceptually similar all 517 documents in the cluster are.