Cluster analysis is a technique used for classification of data in which data elements are partitioned into groups called clusters that represent collections of data elements that are proximate based on a distance or dissimilarity function.

The Season 1pilot
(2005) and Season
2 episode "Dark
Matter" of the television crime drama NUMB3RS feature clusters and
cluster analysis. In "Dark Matter," math genius Charlie Eppes runs a cluster
analysis to find connections between the students that seemed to be systematically
singled out by the anomalous third shooter. In Season 4 episode"Black
Swan," characters Charles Eppes and Amita Ramanujan adjust cluster radii
in their attempt to do a time series analysis
of overlapping Voronoi regions to track the movements
of a suspect.

Kaufman, L. and Rousseeuw, P. J. Finding Groups in Data: An Introduction to Cluster Analysis. New York: Wiley, 1990.Rousseeuw,
P. J. "Silhouettes: A Graphical Aid to the Interpretation and Validation
of Cluster Analysis." J. Comput. Appl. Math.20, 53-65, 1987.Tibshirani,
R.; Walther, G.; and Hastie, T. "Estimating the Number of Clusters in a Dataset
Via the Gap Statistic." J. Royal Stat. Soc. B63, 411-423, 2001.