3.8 Service dogs. A study measured the health-related quality of life (HRQOL) of 126 persons with a disability or illness. The researchers compared the HRQOL of 50 persons who currently lived with a service dog with 76 persons who were on a waiting list to receive one. The researchers concluded that those who lived with a service dog had better emotional HROOL than those who did not. 5 Is this an observational study or an experiment? Is it a sample survey? If it is an experiment, what is the intervention? Explain your answers