Stratified sample
Group into homogenous than take simple random sample
Simple random design
Select randomly
Systematic sample
Randomly pick place to start then take every 10th one after that
Cluster sample
Group by area then randomly select cluster and survey everyone in the cluster
Voluntary response bias
Self selection
Convenience sampling bias
Ask people who are easy to ask
Under coverage bias
People are left out
Non response bias
People don’t respond but are chosen
Response bias
Giving wrong answer for some reason
Wording of question
Changes response the way you ask