Hand rehabilitation systems that use virtual reality (VR) technology have been developed for patients with disabled hands and arms. In Robotica (Vol. 22, 2004), mechanical and systems engineers assessed the effectiveness of display devices for three VR-based hand rehabilitation systems. System A employs a projector to manipulate VR simulation, System B uses a desktop computer monitor, and System C uses a head-mounted display. Twelve nondisabled, right-handed male subjects were randomly assigned to the three VR systems, four subjects in each group. Each subject was required to carry out a “pick-and-place” procedure using the VR system. The variable of interest to the engineers was collision frequency, measured as the number of collisions between moved objects. One objective of the study was to compare the mean collision frequencies of subjects in the three VR-based hand rehabilitation systems.

a. Identify the experimental units for this study.

b. Identify the treatments.

c. Identify the dependent variable.

d. Explain why a completely randomized design was employed to collect the data.

e. Propose a regression model that will allow you to compare the means.

f. Give the null and alternative hypotheses for the ANOVA F test.

g. The ANOVA F test was found to be nonsignificant at α = .05. Give a practical interpretation of this result.