Naturalistic observation, interviews, and case studies
Explanation:
Three of the most common research methods are naturalistic observation, interviews, and case studies. Each one of them brings something different to the table:
Naturalistic observation refers to studying subjects directly on their environment without any intervention from the researcher. This is a great method because watching people behave in a natural way will be very revealing and more truthful. When subjects know they are being observed, they often change their behaviour. Naturalistic observation thus requires the observer to be as anonymous and invisible as possible.
An interview is a research method where the subject is asked to answer to some specific questions crafted by the researcher. Interviews allow the researchers have a much closer look at the subject, trying to ascertain the motives behind their behaviour. However, a problem with interviews is that the subjects often time won't respond truthfully, but will adjust their answers to what is expected from them.
A case study is a method that goes more in depth than the other two, and the researcher tries to learn as much as possible about the subject through a variety of other methods, like observations, interviews, surveys, etc. Case studies are much thorough and deeper investigations, but they can be very time consuming, and require a subject that is willing to facilitate the work of the researcher, which isn't always possible.
Civilizations expand through trade, conflict, and exploration. Usually, all three elements must be present for a civilization to grow and remain stable for a long period of time.
Explanation:
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