We present a new methodology for use in automated monitoring of a syst
em to detect abnormal or degraded system behavior. The methodology use
s the singular value decomposition technique of matrix algebra to disc
over relationships between the elements of data observed from a normal
ly operating system. It then tests these relationships against newly a
cquired data to detect system malfunctions. Based on a theory for syst
em identification in the presence of nuisance parameters, distribution
theory developed specifically for this application allows the system
monitor to properly set threshold levels so as to control the false al
arm rate. The algorithm is numerically stable and relatively easy to a
pply, and was tested successfully on data from a motorized globe valve
in a nuclear power plant. (C) 1997 Elsevier Science Ltd.