Building a combined RP/SP survey in SurveyEngine
A combined RP/SP survey collects both revealed and stated preference data from the same respondents. The survey design must be sequenced correctly or the SP choices will be anchored by the RP data.
How to design a combined RP/SP transport survey in SurveyEngine, including sequencing, reference data collection, and data export.
Knowledge Base -> Survey Building -> Transport
Ben White, 07.07.2026
The survey structure challenge
A combined RP/SP survey first collects the respondent's actual mode choice and journey characteristics (RP data), then presents a series of stated preference choice tasks (SP data). The two datasets are matched on respondent ID for joint estimation.
Sequencing matters. Collecting SP choices before RP data can anchor revealed preferences toward the SP alternatives. The standard protocol collects RP data first, then SP choices.
Best practices for RP/SP survey structure
Joint RP/SP estimation requires that both datasets contain the same respondents. A survey design that loses respondents between the RP and SP sections - through dropout or incomplete responses - produces an unmatched dataset that cannot be used for joint estimation.
The RP data must be collected at a level of detail that allows the SP pivot levels to be computed correctly. Under-specified RP questions produce ambiguous reference values.
TLDR Quick links
Building the combined survey in SurveyEngine
Step 1: Collect RP data first. Ask about the respondent's most recent relevant journey before the SP choice tasks.
Step 2: Collect sufficient RP detail. For a mode choice study, collect: mode used, journey time, cost, number of transfers, departure time, and frequency of delays.
Step 3: Use the RP data to compute SP pivot levels. Configure SurveyEngine derived values to compute SP attribute levels from the collected RP values.
Step 4: Embed a practice choice task. Before the main SP tasks, present one practice task with feedback to familiarise respondents with the choice format.
Step 5: Export RP and SP data in matched format. The export file should contain one row per respondent with RP variables and choice variables in the same record.
Worked example - urban mode choice combined survey
A combined RP/SP survey for a high-speed rail corridor collects RP data on the respondent's most recent intercity journey: mode, journey time, fare paid, number of changes, departure time. The SP experiment presents high-speed rail as a new alternative alongside the current modes, with attribute levels pivoting from the reported RP journey.
Of 450 survey completions, 7 are lost due to incomplete RP data (respondents who refused the fare question). The remaining 443 are exported as a matched dataset for joint Apollo estimation.
References
Hensher, D.A., Rose, J.M. and Greene, W.H. (2015). Applied Choice Analysis. Cambridge University Press.
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