Which one of the following instances is MOST like a random sample for a class of thirty students?
A. A coin is tossed in order to select students alternately one by one into the experimental and control groups.
B. The first ten students who enter the classroom are placed into the experimental group and the next ten into the control group.
C. The first twenty volunteers are selected from the physics class and alternately placed into experimental and control groups.
D. The twenty students with the highest GPAs are selected and alternately placed into experimental and control groups.
Answer:A
Which one of the following instances is MOST like a random sample for a class of thirty students?
A. A coin is tossed in order to select students alternately one by one into the experimental and control groups. B. The first ten students who enter the classroom are placed into the experimental group and the next ten into the control group. C. The first twenty volunteers are selected from the physics class and alternately placed into experimental and control groups. D. The twenty students with the highest GPAs are selected and alternately placed into experimental and control groups.
Explanation: A) A random sample is one in which each subject has an equal opportunity to be selected for any group. The three situations described in the alternative answers to this question all concern special, rather than randomly composed, groups of students. Thus, identifying the experimental groups by coin tossing is the method that most closely approximates a random selection.