Omar's goal as a researcher is to examine behavior as unobtrusively as possible, by observing people in real-world settings. It sounds like Omar is most interested in doing...

Which of the following are true and/or characteristic of interviews?

I. Tend to be open ended.

II. Cheaper and easier to administer than questionnaires.

III. Allow a researcher to obtain more nuanced responses from participants.

What is the primary reason that experiments are so valuable in research?