It depends on the question: How survey format shapes the measurement of public attitudes to carbon capture and storage in Norway

Public attitudes towards emerging, technically complex climate technologies are difficult to measure with standard closed-ended items. When an issue is unfamiliar and low in salience, closed formats may invite low-effort, weakly held answers that mask uncertainty and ambivalence. We examine how question format shapes the measurement of public support for carbon capture and storage, using a probability-based online survey of the Norwegian public fielded in 2020 ( n = 3068). Respondents read a brief information text, wrote an open-ended response, then answered a closed forced-choice item. The two formats yield different pictures of opinion. In their own words, 26% of respondents gave unqualified support and 30% supported the technology only conditionally; the combined positive share was 56%, against 66% in the closed item. ‘No opinion’ was selected by 23% in the closed item but appeared in only 4% of the open-ended responses, whereas non-response was higher for the open question (14% vs. 0.4%). Among respondents selecting ‘No opinion’ in the closed item, around 60% expressed a substantive evaluation in open text, often ambivalent, conditional or negative. Respondents whose open text was not positive but who nonetheless chose ‘Positive’ wrote longer, not shorter, responses. Environmental impacts, leakage, safety, costs and efficacy dominate the reservations expressed. These patterns point to a measurement trade-off: closed items are efficient but may overstate support and understate complexity, whereas open items capture ambivalence at greater respondent burden. Pairing the two formats provides a practical diagnostic of the attitudinal complexity that a single closed-ended item conceals.