The major tasks of clustering evaluation include the following:

    • Before you start: Assess clustering tendency. Assess whether a non-random structure exists in the data. Clustering analysis on a data set is meaningful only when there is a non-random structure in the data.
    • Next: Determine the number of clusters in a dataset. How many clusters are there to find? Like k-means, many methods require the number of clusters in advance as a parameter to the method.
    • After clustering: Measure the clustering quality. There are various quality measures according to different criteria.