Researchers wanted to determine whether the stomach shrinks as a result of dieting. To do this, they randomly divided 23 obese patients into two groups. The 14 individuals in the experimental group were placed on a diet that allowed them to consume 2508 kilojoules (kJ) per day for 4 weeks. The 9 subjects in the control group ate as they normally would. To assess the size of the stomach, a latex gastric balloon was inserted into each subject’s stomach and filled with the maximum amount of water that could be tolerated by the patient.
The volume of water was compared to the volume that could be tolerated at the beginning of the study. The experimental subjects experienced a 27% reduction in gastric capacity, while the subjects in the control group experienced no change in gastric capacity. It was concluded that a reduction in gastric capacity occurs after a restricted diet.
(a) What type of experimental design is this?
(b) What is the population that the results of this experiment apply to?
(c) What is the response variable in this study? Is it qualitative or quantitative?
(d) What are the treatments?
(e) Identify the experimental units.
(f ) Draw a diagram similar to Figure 7 or 8 to illustrate the design.