Q1. Study designs, why so many?

Analytic Epidemiology is all about actual studies….the testing / examining the hypothesis’ garnered from Descriptive Epidemiology.
Why are there so many different types of studies? Are they really different?
(lots of leeway here, so let’s see where we go)

(Each question will need references and should be more than 200 words without references)

Q2. Q2: Tag, you’re it

Pick a type of Analytic study and explain it (what is it, how do you set it up, what are you looking for, how is it run), and please give an example or 2….hypothetical’s are fine to use.
Lot’s of leeway here.

(Each question will need references and should be more than 200 words without references.)