Question

ch 21 researchers compared the balance of a sample of elderly patients with that of a separate sample of younger patients. they exposed members of each age group to unpredictable noises and measured the amount of forward and backward sway. what feature of this study suggests that two - sample inferences for the means of the groups might be appropriate? both groups were exposed to the same noise. the two groups were sampled independently. both were groups of patients. the noise was unpredictable.

Explanation:

Two - sample inferences for means are appropriate when the two samples are independent. In this study, the sample of elderly patients and the sample of younger patients are separate (sampled independently). The fact that both groups were exposed to the same noise (or that the noise was unpredictable) is about the experimental condition, not about the sampling method for the two - sample inference. And the fact that both are groups of patients is just a general characteristic of the participants, not relevant to the independence of the samples.

Answer:

The two groups were sampled independently.