A system for detecting positioning effect in a body, comprising: a signal output operable to couple directly or indirectly to a stimulating electrode to deliver a plurality of time-locked electrical stimulus to a peripheral nerve in the body; a signal input operable to couple directly or indirectly to a recording electrode to record a plurality of resultant electrical waveforms generated by the body's nervous system in response to the time-locked electrical stimulus; a signal generation circuit and/or processor coupled to the signal output and the signal input and configured to cause the signal output to generate the electrical stimulus and the signal input to receive the plurality of resultant electrical waveforms; and a detection processor configured to detect a positioning effect by comparing the processed resultant electrical waveform to a moving baseline waveform, characterized in that the moving baseline waveform is established by: developing an initial baseline waveform from an average of the plurality of resultant electrical waveforms; upon the delivery by the signal output of an additional electrical stimulus to the peripheral nerve in the body, determining if the additional resultant electrical waveform is good by comparing the additional resultant electrical waveform to the initial baseline; if the additional resultant electrical waveform is good, developing an updated baseline waveform, wherein the updated baseline waveform is a weighted average of the initial baseline waveform and the additional resultant electrical waveform; and if the additional resultant electrical waveform is not good, setting the updated baseline waveform to the initial baseline waveform. a signal output operable to couple directly or indirectly to a stimulating electrode to deliver a plurality of time-locked electrical stimulus to a peripheral nerve in the body; a signal input operable to couple directly or indirectly to a recording electrode to record a plurality of resultant electrical waveforms generated by the body's nervous system in response to the time-locked electrical stimulus; a signal generation circuit and/or processor coupled to the signal output and the signal input and configured to cause the signal output to generate the electrical stimulus and the signal input to receive the plurality of resultant electrical waveforms; and a detection processor configured to detect a positioning effect by comparing the processed resultant electrical waveform to a moving baseline waveform, developing an initial baseline waveform from an average of the plurality of resultant electrical waveforms; upon the delivery by the signal output of an additional electrical stimulus to the peripheral nerve in the body, determining if the additional resultant electrical waveform is good by comparing the additional resultant electrical waveform to the initial baseline; if the additional resultant electrical waveform is good, developing an updated baseline waveform, wherein the updated baseline waveform is a weighted average of the initial baseline waveform and the additional resultant electrical waveform; and if the additional resultant electrical waveform is not good, setting the updated baseline waveform to the initial baseline waveform.