Case studies involve what methodologists call thick  rich, full information that should come from multiple data sources, particularly from firsthand observations.
Firsthand observation are treated as a rich source of information by the methodologists.
There is only one source of information for the case studies of methodologists.
Several men are grouped around a table.
Self-interest is behind our actions, we don't do it out of philanthropy.
Indian food is srtong.
A readheaded woman slept on the street
Nebbishes are so pathetic, people won't even contemplate them/
It is difficult to read the emotions of an Indian person.