In the developed world the importance of evidence-based policy is increasingly recognised. Panel studies – a long-term study design where a cross-sectional sample of units is selected and surveyed at regular intervals – are being used to gather information about the same people or...

Accompanying the call for increased evidence-based policy the developed world is implementing more longitudinal panel studies which periodically gather information about the same people over a number of years. Panel studies distinguish between transitory and persistent states (e.g. poverty,...