Question 7.57
27. We want to investigate the following question: Will classroom programs explaining the health advantages of drinking water rather than sugary sodas reduce obesity among children aged 7 to 11 years? Because children are already grouped in school classrooms, we must randomize classes rather than individual children. An experiment assigned 15 classes to receive the program and another 14 to form a control group. After 12 months, obesity had increased in the control group and remained steady in the treatment group. Outline the design of the experiment, label the available classes, and use Table 7.1 (page 298), beginning at line 103, to carry out the random assignment.
27.
The design resembles Figure 7.3 (page 307).
Be sure to show randomization, two groups and their treatments, and the response variable (change in obesity).
If we label the 29 classes 01 to 29 and choose 15 for the treatment group, this group contains classes 17, 09, 22, 13, 07, 02, 27, 01, 18, 25, 29, 19, 14, 15, and 8. We used lines 103 to 106 of Table 7.1 (page 298), skipping any duplicate pairs of digits. In order, these classes are 1, 2, 7, 8, 9, 13, 14, 15, 17, 18, 19, 22, 25, 27, and 29. The remaining 14 classes make up the control group.