To investigate a possible association between exercise and depression, a researcher had 30 volunteers who suffer from depression and 30 volunteers who do not suffer from depression keep activity journals for one month. He then used the information in the journals to determine how much each person exercised. The resulting data were then used to compare activity for the two groups. This is an example of

A. A census
B. A random sample
C. An experiment
D. An observational study



Answer :

Final answer:

Observational studies involve collecting data without altering variables, enabling comparison between groups based on natural behaviors.


Explanation:

An observational study involves gathering data without manipulating the independent variable. In the scenario described, the researcher observed the subjects' exercise habits without intervening or assigning them specific exercise routines. This method allowed for a comparison between two groups based on natural behaviors.


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