Finding out what people want: a case study of preference elicitation using a multi-

criteria methodology

David Whitmarsh and Maria Giovanna PalmieriCEMARE, Department of Economics

PBS Research Conference, September 27th 2006

Background: the ECASA project

• CEMARE is a partner in a EU funded Framework Six project (ECASA) investigating the environmental impacts of aquaculture.

• Our role is to find out about the social acceptability of aquaculture development, based on a preference elicitation methodology. (i.e. What do people want from aquaculture ?)

• Study area: Scotland, where salmon farming has contributed to economic development but generated controversy over its environmental performance.

• Methodology: Questionnaire surveys of (i) the general public,

differentiated by region (ii) key stakeholder groups Preferences will be elicited using the Analytic Hierarchy

Process (AHP), originally developed by Saaty (1977)

ECASA preference elicitation survey: study sites

Source: Scottish Association for Marine Science

Surveying the Scottish general public

• Survey population: Households in the main coastal areas of Scotland, where salmon farming is most widely practiced.

• Selection of respondents: Random sampling, having regard to the need to ensure coverage in each of the five study sites.

• Sample size: 5000 names and addresses selected from the Electoral Registers for Scotland (1000 to each study site).

• Data collection: Self-administered questionnaires sent by mail to named householders, plus a reply-paid envelope and accompanying letter.

• Follow-up: Postcards to be sent to all respondents (thanks or reminder).

Structure of the questionnaire

• Introduction. Explanation of the positive and negative effects of salmon farming.

• Respondents are then asked questions within three sections:

• Section A: To compare the various objectives of the salmon farming industry and to rate their relative importance.

• Section B: To express an opinion on what they think would be better for Scotland in terms of future salmon farming development.

• Section C: To supply information about themselves (i.e. attribute variables, including: age, gender, household size, qualifications, employment, membership of environmental groups, postcode, etc.), plus any other comments.

The Analytic Hierarchy Process (AHP)

• AHP is a multi-criteria decision method that enables qualitative judgements about the relative importance of different objectives to be converted to numerical scores.

• The technique has been applied to a range of decision problems, including natural resource use and conservation (Mardle & Pascoe, 1999 & 2003; Mardle et al. 2004; Wattage and Mardle, 2005)

• In the present study, AHP is relevant because the performance of the aquaculture industry covers multiple dimensions (e.g. economic, social, environmental, etc.)

• Respondents are asked to make pairwise comparisons between different objectives or criteria, where the intensity of preference is measured on a scale (9-point or 5-point).

• Responses can be converted to scores to show the priority attached to different objectives and criteria.

Hierarchy of objectives for Scottish salmon aquaculture

Goal Objectives Criteria

Maximise net benefits

Maximise socio-economic benefits

Minimise environmental damage

Sustaining employment and livelihoods

Enhancing edible fish supplies

Contributing to tax revenues

Minimising pollution and water quality impacts

Minimising visual intrusion and landscape impacts

Minimising impact on wild salmon stocks

Pairwise choices of objectives and criteria

Accessing other socio-economic data

• Responses to some questions involve discrete choices (e.g. attitude to aquaculture development)

• Logistic regression can be used to predict the probability of response from other data (e.g. location, occupational status, etc.)

Explaining attitudes: logistic regression

How might the study be useful ?

• Results will be provide information to policy-makers on:

How people evaluate the trade-off between the beneficial effects of aquaculture (job creation, etc.) and the negative effects associated with environmental degradation.

Whether there are significant areas differences in attitudes towards aquaculture development; if there are, it may be relevant to site selection.

Factors affecting public attitudes, specifically the influence of neighbourhood variables such as unemployment rate and income.

Acknowledgement

• This presentation has been prepared with support by the European Commission project ECASA (Ecosystem Approach for Sustainable Aquaculture), Contract No. 006540