Table 1 Definitions used ^a

Key event

Change to a setting (physical, social, political, fiscal or organisational) or individual circumstance that is unrelated to the financial incentives studied within the parent RCT. These include changes primarily intended to alter travel behaviour (e.g. a new bus timetable), and changes capable of altering travel behaviour but not primarily intended to do so (e.g. new local amenities, having a child)

Context

The physical, social, political, fiscal or organisational conditions of the setting in which the event occurs (e.g. the existing bus network) and/or the physical, social or political characteristics of the individual exposed to the event (e.g. bicycle ownership, ability to cycle)

Mechanism

The process by which a key event interacts with people in a particular context to lead to travel behaviour change, including the reasoning of how people or populations responded to the key event. This process may be observable or hidden.

Outcome

Any change in travel mode reported by a participant, including changes for a single journey or multiple ongoing changes