Do the twist Th e design of controls and instruments has a large eff ect on how easily people can use them. A student investigates this eff ect by asking righthanded students to turn a knob (with their right hands) that moves an indicator by screw action. Th ere are two identical instruments, one with a right-hand thread

(the knob turns clockwise) and the other with a left -hand thread (the knob must be turned counterclockwise). Th e response variable is the time required (in seconds) to move the indicator a fi xed distance. Th irty right-handed students are available to serve as subjects. You have been asked to lay out the statistical design of this experiment. Describe your design, and carry out any randomization that is required.