3.20 Use the Simple Random Sample applet. The Simple Random Sample applet can demonstrate how randomization works to create similar groups for comparative experiments. Suppose that (unknown to the experimenters) the first 20 students among the 40 subjects for the smartphone study in Example 3.18 (page 166) tend to send more text messages than the students numbered 21 to 40. We would like the two groups to be similar with respect to text messaging. Use the applet to choose 10 samples of size 20 from the 40 students. Record the counts of students numbered 1 to 20 in each of your 10 samples. You see that there is considerable chance variation but no systematic bias in favor of one group or the other in assigning the fast-reacting students. Larger samples from larger populations will, on the average, do a better job of making the two groups equivalent.