D.3 Answers: Research designs

Answers to exercises in Sect. 3.10.

Answer to Exercise 3.1: The researchers could decide which beams go into Group A and into Group B. Researchers could also allocate treatments to the groups: they could select what treatments is applied to each group of beams. This is a true experiment.
Answer to Exercise 3.2: The researchers had no say in who was in hospital at the time: they could not allocate the patients to the two groups (overlay; matress). this is a quasi-experiment.
Answer to Exercise 3.3: 1. P: Perhaps people in a suburb of the Sunshine Coast; O: number of doctor’s visits in the next six months; C: between people owning a pet for those six months, and those who do not own a pet for those six months. 2. For an experiment, we would need to intervene to give subjects a pet, or not give them a pet. 3. For an observational study, we would not intervene: We would find the subjects who already owned a pet, or who did not already own a pet.
Answer to Exercise 3.4: 1. P: A bit vague from this small extract: people of some kind; O: the average change in body weight over two years; C: Between the four diets; I: The diets seems to be have been imposed. 2. Experimental: The diets have been imposed by the researchers, with the intent of changing the outcome (the weight change). 3. Probably a true experiment. 4. The individuals: those from whom the weight change is taken. 5. The individuals: the diets are allocated to each individual. 6. The change in body weight over two years. 7. The type of diet.