PBS
Pbs Learning Media: Using Data Clusters to Find Hacker
The CyberSquad searches for Hacker's castle based on a survey of where town residents have last seen him in this video from Cyberchase.
Other
Correlation Coefficients
This page provides a good discussion of correlation coefficients (r,) which indicate the "strength of the linear association between variables." Includes formulas and scatter plots. Some prior knowledge of statistics might be helpful.