Detecting and handling protest responses in environmental DCEs

Protest responses in environmental DCEs are not data quality failures - they are genuine expressions of objection to the study design. But they must be identified and handled correctly.

This article explains what protest responses are in environmental DCEs, how to detect them using debriefing questions in SurveyEngine, and how to report them in line with best practice.

Ben White, 07.07.2026

What are protest responses?

A protest response in an environmental DCE is when a respondent consistently chooses the status quo (no change, no cost) not because they genuinely prefer the current situation but because they object to something about the study design - typically the payment vehicle, the delivering institution, or the principle of monetising environmental goods.

Protest responses look identical to genuine status quo preference in the choice data. Without a debriefing question asking respondents to explain their reasoning, you cannot distinguish a genuine zero-WTP respondent from a protestor. Including protesters in the main analysis biases WTP estimates downward - excluding them without justification biases them upward.

Why protest responses are a methodological challenge, not just noise

The literature on protest responses in environmental valuation is extensive and contested. Some researchers argue that protest responses should always be excluded because they represent a failure of the stated preference exercise. Others argue they should be included as legitimate expressions of political preference - a valid response to the monetisation of nature.

The consensus in the environmental economics literature is that protest responses should be identified, reported, and handled in sensitivity analyses. The main analysis should include all respondents; sensitivity analyses should exclude protesters and report the impact on WTP estimates. Both estimates should be presented, with discussion of the implications.

SurveyEngine includes a debriefing module for environmental DCEs that collects the information needed to classify protest responses according to the widely used taxonomy of Jorgensen and Syme (2000).

TLDR Quick links

Environment resources

Protest pre-check article

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Detecting protest responses in SurveyEngine

Step 1: Add a debriefing question after the choice tasks. If the respondent always (or mostly) chose the status quo alternative, show them a debriefing question: 'You chose the current situation in most choice sets. Which of the following best explains your choices?'

Step 2: Provide both genuine preference and protest response options. Include options that cover both genuine status quo preference (I prefer the current situation; I cannot afford additional costs) and protest responses (I don't trust the authority to deliver improvements; I object to paying for something the government should fund; I don't think money can capture the value of nature).

Step 3: Show the debriefing question only to consistent status quo choosers. Use display logic in SurveyEngine to show the debriefing question only to respondents who chose the status quo in 6 or more of 8 tasks.

Step 4: Classify respondents based on debriefing responses. Code each consistent status quo chooser as either a genuine zero-WTP respondent (selected a preference-based reason) or a protest respondent (selected a protest reason). Use a conservative classification that treats ambiguous cases as genuine.

Step 5: Run and report sensitivity analyses. Estimate WTP models including all respondents, excluding protesters, and (if sample size permits) for the genuine zero-WTP sub-sample separately. Report all three estimates with confidence intervals.

Worked example - peatland restoration WTP study

An environmental DCE valuing peatland restoration finds 28% of respondents chose the status quo in 7 or 8 of 8 tasks. Debriefing reveals: 31% of these are genuine zero-WTP (cannot afford it, or genuinely prefer the current management); 52% are protesters (don't trust the Environment Agency, object to taxation, or don't think nature should be monetised); and 17% are ambiguous.

Main analysis WTP (all respondents): £28/year. Sensitivity analysis excluding protesters: £42/year. The 50% difference is reported with discussion of the protest response rate and its implications for the policy decision.