On the Definition and Use of Aggregate Indices for Nominal, Ordinal, and Other Scales.

Sandro Morasca On the Definition and Use of Aggregate Indices for Nominal, Ordinal, and Other Scales. 46-57 2004 conf/metrics/2004 IEEE METRICS http://csdl.computer.org/comp/proceedings/metrics/2004/2129/00/21290046abs.htm db/conf/metrics/metrics2004.html#Morasca04