Fig. 1.  Box-and-whisker plots for derived electroencephalographic measures as a function of the Observer's Assessment of Alertness/Sedation (OAA/S) level for no remifentanil (remi0), 2 ng/ml remifentanil (remi2), and 4 ng/ml remifentanil (remi4) treatment groups. Boxes  represent interquartile ranges, lines enclosed within boxes  (and connected lines ) median values, whiskers  represent the largest (smallest) nonoutlier, and circles  represent outliers (defined as values extending further than 1.5 times the interquartile range—equivalent to approximately 3 SDs for normally distributed data). (A ) Cortical Input (CI), (B ) Cortical State (CS), (C ) root mean square (RMS) electroencephalogram amplitude, and (D ) electromyogram (EMG).