Clusters

Sometimes the cloud of crosses separates into two or more groups which are called clusters. As with outliers, clusters provide important information that should be further investigated.

Again, the individuals should be further examined (perhaps collecting further information from them) to try to assess whether the clusters correspond to individuals with distinct characteristics. For example, the clusters may correspond to males and females, or to two different species of plant.

Iris sepals from the Gaspé Peninsula

If the data seem to separate into clusters, you should check whether they correspond to distinct types of individual with regard to other characteristics.