How many key informants are enough? Analysing the validity of the community readiness assessment.

A total of 55 community readiness interviews were carried out in 4 communities. Overall, the community readiness scores showed little variation after having interviewed 10 key informants in a community. However, even after completing 10 interviews in a community, key informants were still able to identify up to 6 new information items regarding community efforts for physical activity promotion among the elderly, contact and communication channel for informing or approaching the target group, or barriers to participation.