Who? How many? Selection? Sorted?
Basis for participation
All the units we would like to study
The people who are the focus of the research
A group of people who represent the population
Keep record of:
Number screened out and why
Number dropped out and why
To estimate how closely sample statistics are clustered around the true population value.
Randomness (sample with replacement)
Randomness is necessary in order to use powerful statistics!