If it is the responsibility of a regulatory body to decide where to prioritise future investment, then it is important to
understand the priorities of the citizenry it represents. This paper, in collaboration with the OECD and the Scottish water
industry, presents the results of an online (n= 500) and face-to-face laboratory (n= 99) study that utilised experimental
behavioural science to explore how Scottish citizens trade-off costs and potential improvements to their water service.
Participants’ priorities for investment were elicited using a novel ‘slider task’ methodology that forced them to explicitly
consider the trade-offs required to allocate limited resources across multiple possible water service improvements. The provision
of additional cost and timing information was systematically varied. Results suggest that citizens are increasingly accepting of
price rises when provided this information. Results also suggest that citizens’ priorities for specific improvements are not
sensitive to the costs of different improvements but are sensitive to the lengths of time improvements take to be made. Findings
from this study are designed to inform the regulatory process of the Scottish water industry and highlight the potential role of
behavioural science in regulation more generally