The K-Means Cluster Analysis procedure begins with the construction of initial cluster centers. You can assign these yourself or have the procedure select k well-spaced observations for the cluster centers.

After obtaining initial cluster centers, the procedure:

- Assigns cases to clusters based on distance from the cluster centers.
- Updates the locations of cluster centers based on the mean values of cases in each cluster.

These steps are repeated until any reassignment of cases would make the clusters more internally variable or externally similar.