Which statements are true about observational studies? Choose all correct answers. a. Observational studies involve manipulation of dependent variables.
b. Observational studies have negative controls but not positive controls.
c. Observational studies have both independent and dependent variables.
d. Observational studies can be used to test hypotheses.
e. Observational studies do not have either independent or dependent variables.
f. Observational studies do not involve manipulating independent variables.
g. Observational studies do not have controls.

c. Observational studies have both independent and dependent variables.

d. Observational studies can be used to test hypothesis.

Explanation:

Observational studies are ones in which a researcher makes observations about his thoughts and views. He observes the risk and other effects before actual test takes place. This is usually the initial phase of research where observations are made for suitability of certain things that are to be researched. There is initial feasibility test conducted to identify whether the further research process is beneficial or not.

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