A sample from which information is collected over time. It can be questioned several times at regular intervals. This method is pertinent for studying changes in behaviour.
The sample can be questioned continuously:
- either: each individual in the panel is asked to fill in a daily questionnaire relating to the subject of the study. This is the case for the Radio panel.
- or the information is recorded and returned regularly. This is the case for the Médiamat panel. This method is pertinent for understanding behavioural patterns and their changes if the panel lasts long enough.