Random
Sampling

Stratified
Sampling

Systematic
Sampling

Quota
Sampling

Snowball
Sampling

Opportunistic
Sample

Anonymity

Confidentiality

Informed
Consent

Gatekeeper

Safety

Qualitative
Data

Qualititative
Data

Participant
Observations

Non-participant
Observation

Overt
Observation

Covert
Observation

Unstructured
Interviews

Open ended
Questionnaires

Focus group

Longitudinal
Study

Structured
Interviews