title: The identification of credit card encoders by hierarchical cluster analysis of the jitters of magnetic stripes.
abstract: The relative bit density variation graphs of 207 specimen credit cards processed by 12 encoding machines were examined first visually, and then classified by means of hierarchical cluster analysis. Twenty-nine credit cards being treated as 'questioned' samples were tested by way of cluster analysis against 'controls' derived from known encoders. It was found that hierarchical cluster analysis provided a high accuracy of identification with all 29 'questioned' samples classified correctly. On the other hand, although visual comparison of jitter graphs was less discriminating, it was nevertheless capable of giving a reasonably accurate result.
authors.affiliation: Forensic Science Division, Government Laboratory, Kowloon, Hong Kong, China.
authors.forename: S C
authors.initials: SC
authors.lastname: Leung
authors.forename: W K
authors.initials: WK
authors.lastname: Fung
authors.forename: K H
authors.initials: KH
authors.lastname: Wong
mesh_terms: D016000:Cluster Analysis; D005554:Forensic Medicine / Q000379:methods*; D005607:Fraud; D006801:Humans; D008280:Magnetics