Question

In a study published on January 31, 2011 in The Proceedings of the National Academy of Sciences, researchers randomly assigned 120 elderly men and women who volunteered to be a part of this study (average age mid-60s) to one of two exercise groups.

One group walked around a track three times a week; the other did a variety of less aerobic exercises, including yoga and resistance training with bands.

After a year, brain scans showed that among the walkers, the hippocampus (part of the brain responsible for forming memories) had increased in volume by about 2% on average; in the others, it had declined by about 1.4%.

Which of the following is false?

a. A causal link between walking and expansion of the hippocampus can be inferred based on these results.

b. The explanatory variable is the type of exercise.

c. The response variable is the change in volume of the hippocampus.

d. The results of this study can be generalized to all elderly.

Answer 1

d.

Explanation:

Hello!

The objective of this test is to know if aerobic exercise modifies hippocampus activity. A random sample of 120 elderly men and women was taken and divided into two groups.

Group 1: Walked around a track three times a week.

Group 2: Did a variety of less aerobic exercises, including yoga and resistance training with bands.

After a year their brains were scanned showing that group 1 had an increase of 2% in their hippocampus and group 2 showed a decrease of 1.4%

a. True, this type of observational study can be the prelude to a more formal statistical study.

b. True, the explanatory variable is "type of exercise", it's the variable that the investigator suspects influence the hippocampus volume.

c. True, the objective of this experiment is to test if there is any modification on hippocampus volume, that's why the volume of the hippocampus was measured, before and after a year of exercise.

d. False, this is an observational study, you cannot establish a causal relationship between the two variables. Just inform you that there seems to be an association. To be able to generalize the results to all elderly population you need a more formal statistical experiment to support your conclusions.

I hope it helps!