researchers periodically survey a few thousand of the patients taking a certain medication in order to make…

researchers periodically survey a few thousand of the patients taking a certain medication in order to make connections between that medication and the subjects general health. this method of gathering data is classified as\na census.\na sample survey.\nan experiment.\nan observational study.

researchers periodically survey a few thousand of the patients taking a certain medication in order to make connections between that medication and the subjects general health. this method of gathering data is classified as\na census.\na sample survey.\nan experiment.\nan observational study.

Answer

Brief Explanations:

A census involves collecting data from an entire population. Here, only a few - thousand patients (a subset of all patients taking the medication) are surveyed, so it's not a census. An experiment involves manipulating variables. Since no manipulation is done here, it's not an experiment. A sample survey is a type of observational study. The researchers are observing the patients' general health in relation to the medication without interfering, which is characteristic of an observational study.

Answer:

D. an observational study.