1. SAMPLING

2. Voluntary Response Individuals choose to join the sample in response to an open invitation.

3. Random Sample When everyone (thing) has the same chance of being selected.

4. Systematic Sampling Sampling from a population according to a random starting point and a fixed, periodic interval.

5. Stratified Sampling Divide the population into groups that have something in common, then randomly select from each group.

6. Cluster sampling Divide the population into groups of individuals (things) that are near each other. Randomly select some of the groups and included all the individuals (things) in those groups.

7. Convenience sampling Choose individuals (things) that are easiest to reach.