Fig. 2.  Examples of synthetic 2-s epochs of electroencephalogram data illustrating the independence of Cortical Input (CI) and root mean square (RMS) electroencephalogram amplitude. Each column of this figure represents a realization of a fixed autoregressive moving average process, estimated from an artifact-free 2-s epoch of electroencephalogram to which a Gaussian white-noise innovation of differing amplitudes was applied. The 2-s electroencephalogram epochs were chosen at random from the recorded electroencephalogram of a patient in the treatment group that received no remifentanil (remi0) at various levels of estimated hypnosis (Cortical State [CS]). Note that for a fixed CS (column-wise), CI and RMS covary, whereas for varying CS (row-wise), CI remains fixed while RMS varies.