Typically in an evaluation study, several types of data might be required. They can be matched up to the research subject as follows:

Information requirement	Data
Understand current rail use	Trip data from current journeys (ie frequency of trips, journey data, journey purpose etc.)
Profile the population of rail passengers	Demographic data (age, gender)
	Home location
	Occupation
	Socio-economic data
	Car availability
	Access to public transport
Satisfaction with aspects of rail travel	Preferences
	Attitudinal data (attitudes towards certain aspects of rail travel, and alternatives)
	Current level of satisfaction with aspects of facilities / services
	Feedback and suggestions
Understanding where respondents are on the behavioural change scale	Current stage of behaviour change to new mobility option (for example are they currently intermittently using rail travel? Or have they tried rail travel and currently deciding whether to continue?
Understanding barriers to more frequent travel	Perceived barriers to more frequent rail travel (such as not being able to carry luggage and equipment to the station)
	Actual barriers to more frequent rail travel (such as where the station is in relation to home)

An important consideration when selecting which type of data to select is to think about the outputs and outlets for the findings of the evaluation. In particular, the end results should be trustworthy and the right choice of data will help this.