Overall, 120 undergraduate students of National Cheng Kung
University in Taiwan participated in the experiments. To avoid
concentration of a certain group in the sample, stratified sampling
was adopted to collect sample of computer users of different age
groups. The research subjects were undergraduates of the day-time
programs and the night-time vocational programs. Greater differences
in age and computer usage experience were expected
between the two groups of students, so the concentration of
a certain group in the sample could be avoided