It is fundamental that for a polygraph chart to
be credible, it must be an exact representation
of only the subject's actual physiological changes.
The signal must be completely linear with no filtering
or altercation. Clearly the Lafayette LX-3000
does not meet this requirement. Note the distortion
of the signal
(in the below graph prepared by the Department
of Defense Polygraph Institute) which is used
by the algorithm for scoring.
