Procedure signals generated by a skilled surgeon and trainee for the same task (T06) are shown. The skilled surgeon generates more consistent task features and less noise between features. Reprinted with permission from Chami G, Ward J, Wills D, Phillips R, Sherman K. Smart tool for force measurements during knee arthroscopy: in vivo human study. Stud Health Technol Inform. 2006;119:85–89. Copyright (2006), with permission from IOS Press.