Re: Data Metrics

Will Dwinnell (76743.1740@CompuServe.COM)
Thu, 23 Jul 1998 00:00:40 +0200 (MET DST)

"does anyone know about approaches to theories on the
definition of a metric for data?

Something like measuring the "distance" between two records,
based on the data they contain..."

This is a well-explored subject for purely numeric data. For
mixed numeric/nominal or purely nominal data, there is less
information. With numeric data, look for "distance metrics" and
"similarity measures" in multivariate statistics. Some common
examples (which may aid in a keyword search) are Euclidean
distance (also known as geometric or L-1 distance), Manhattan
distance (also known as city-block, absolute, maximum or
L-infinity distance) and Mahalanobis distance. Purely nominal
data is sometimes compared using string distances like the
Levenshtein distance.

-- 
Will Dwinnell

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