Table 1

Initial criteria for selection of case study sites

ScaleWhat is the realistic likely impact of the intervention on an identifiable local study population?
SynergyIs the effect of the intervention likely to be enhanced by other concurrent local interventions, or is the evaluation likely to be enhanced by the use of any other locally available datasets?
RiskWhat is the risk that the intervention will not be completed?
ConvenienceIs the intervention site convenient to the research team for the collection of data?
TimescaleWhen is the intervention expected to be completed?
ComparabilityIs it feasible to match the intervention site to a no-intervention control site?
HeterogeneityDoes the overall set of case study sites provide a mixture of contexts (settings), mechanisms and outcomes (eg, travel behaviour change for different journey purposes or in different population groups)?