Random -names = numbers, lottery method to
choose sample - s- internal validity - W- time consuming, may refuse
Systematic- mathematically chosen, nth person, alphabetical order - S- no bias - W- time consuming, may refuse
Stratified- groups of people, some selected fro sample = broad
representation - s- broad representation - W- personal differences
Opportunity- convenience - s- time/ money effective -
W- unrepresentative, possible controlled selection
Volunteer-self-selecting - s- simple, engaged - W- attract a certain Profile