Table 1 Eligibility criteria for studies of whether the effects of transport interventions differ by ethnicity and socio-economic status

‘Equity-focused’ criteria

Inclusion criteria

 • To be eligible, studies must assess whether the impacts of transport interventions differ by ethnicity and socio-economic status (SES). Studies that report effect estimates stratified by SES or ethnicity are eligible, and studies that report whether or not there is an interaction effect between intervention and the ethnicity/SES variable are eligible.

 • Income, education, employment, and housing tenure are eligible measures at individual level. Area deprivation is an eligible area level measure of SES and may be also used as a proxy for individual SES.

Exclusion criteria

 • Studies that only assess whether there is confounding by SES/ethnicity (rather than whether intervention effects differ by SES/ethnicity) are not eligible.

‘Transport intervention’ criteria

Inclusion criteria

 • Studies of transport interventions are eligible. This search focuses on interventions that change the amount (distance or duration) of travel by different modes.

 • Eligible outcome measures include all quantitative measures of health and measures of the amount of travel by different modes (e.g. walking, cycling or car use).

 • Quantitative studies are eligible, including both empirical and modelling studies. Under the ‘empirical’ category, randomised controlled trials, non-randomised controlled trials, controlled before-after (CBA) studies and interrupted time series (ITS) studies are eligible. CBA studies may use geographical exposure to the intervention (e.g. proximity to infrastructure) as a basis for assigning participants to intervention and control groups. ITS studies must include at least two data points before the intervention and one after. In addition, modelling studies that estimate the impact of transport interventions or of specified changes in travel on health outcomes are eligible.

Exclusion criteria

 • Studies that only describe the implementation of transport interventions, and do not assess changes in the amount of travel, are not eligible.

 • Studies that assess change in outcomes through retrospective self-assessment by participants (e.g. ‘do you cycle more now than before the intervention?’), and do not measure the outcome before and after the intervention, are not eligible.

 • Purely qualitative studies are not eligible.