A researcher has recruited 20 volunteers to participate in a study. The researcher wishes to measure the effect of alcohol on an individual’s reaction time. The 20 volunteers are randomly divided into two groups. Group 1 serves as a control group in which participants drink four 1-ounce cups of a liquid that looks, smells, and tastes like alcohol in 15-minute increments. Group 2 will serve as an experimental group in which participants drink four 1-ounce cups of 80-proof alcohol in 15-minute increments. After drinking the last 1-ounce cup, the participants sit for 20 minutes. After the 20-minute resting period, the reaction time to a stimulus is measured.
(a) What type of experimental design is this?
(b) Use Table I in Appendix A or a random-number generator to divide the 20 volunteers into groups 1 and 2 by assigning the volunteers a number between 1 and 20. Then randomly select 10 numbers between 1 and 20. The individuals corresponding to these numbers will go into group 1.