- A survey where multiple observations are obtained from each sampling unit. This is a type of Hierarchical Data. Common examples include:
- Customer satisfaction panels, where the same customers provide ratings of satisfaction over time (e.g., every quarter).
- Television viewing panels, where people’s TV viewing is recorded over time.
- Household purchasing panels, where households purchases are recorded over time.
- Customer records and transactional records (e.g., where an online book seller records each purchase of its customers).
- A list of people willing to participate in market research studies in return for compensation of some kind (also known as an access panel).
- A list of vendors that are authorized to provide a particular service to an organization (e.g., a panel of data science consultancies).