Sampling selects participants or subjects from a population using chance. In experiments, random selection helps connect observed results to the population being studied. section 3.2.3
Choose a selection approach that fits the population and experimental design:
- Use pure random selection when every participant can be chosen directly by chance. section 3.2.3
- Use stratified selection to choose participants in proportion to relevant subgroups. section 3.2.3
- Use clustered selection by dividing participants into groups and randomly selecting at the group level. section 3.2.3
- Keep sampling distinct from random group assignment, which places selected participants into treatment or control groups. section 3.2.3
Sampling is one condition supporting causal experiments, alongside random group assignment, controlled conditions, and direct manipulation of the independent variable. section 3.2.3






















