10-72. The results of a study on powered wheelchair driving performance were presented in the Proceed- ings of the IEEE 24th Annual Northeast Bioengineer- ing Conference (1998. p. 130). In this study. the effects of twu types of joysticks, force sensing (PSI) and position sensing (PSJ), on power wheelchair control were investigated. Each of 10 subjects was asked to test both joysticks. One response of interest is the time (in seconds) to complete a predetermined course. Data typical of this type of experiment are as follows: ___ Subject PS] FSJ ___ 25.9 33.4 2 30.2 37.4 3 33.7 48.0 4 27.6 30.5 5 33.3 27.8 6 34.6 27.5 1 33.1 36.9 8 30.6 31.1 9 30.5 27.1 10 25.4 38.0 ____ Find a 95% condence interval on the difference in mean completion times. [5 there any indication that one joystick is preferable