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 a census. a sample survey. an experiment. an observational study.

An Observational study is the one in which researchers observe the effect of a risk factor, diagnostic test, treatment or other intervention without trying to manipulate or change the results.The condition discussed above lies in observational study because the researchers didn't changed the results or experimented something on any one.

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wagonbelleville wagonbelleville · Answer 2 · 2019-02-15T06:48:42+01:00

Answer:

D. An observational study.

Step-by-step explanation:

We are given that,

'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'.

So, we see that,

The researchers observed the effect of the medication on the patients health.

That is, they used 'Observational Study' in which the independent variable is not under the control of the researcher.

Since, the patients are not under the control of the researcher i.e. they are not bound to take medicines unwillingly.

Hence, the given method of gathering data is 'an observational study'.