MCDA in E-democracy.  Why weight?
Valerie Belton1, George Wright2, Gilberto Montibeller 3,
1 Management  Science , University of Strathclyde, Glasgow, U.K. 
email: val.belton@strath.ac.uk
2 Durham University Business School, Durham, U.K.
3 Business Information Management , Kingston Business School, London, U.K.

Abstract 
The field of environmental decision-making is one which undoubtedly must pay attention to multiple conflicting criteria.  At the same time, it is one that attracts the attention of a wide range of stakeholders, including the public.  Thus, there is clear potential for the use of MCDA and e-democratic technologies and there is interest in their use, as a recent UK invitation to tender illustrates.  However, this is a very different way of working to the traditional decision conference, thus it is important to ask whether the traditional tools of MCDA are well-suited to this new environment.  The work reported in this paper is neither in the field of environmental decision making, nor is it directly concerned with e-democracy.  But it was motivated by a concern which is very relevant to the use of MCDA, in particular the use of aggregate value function methods, in that context – the issue of weights.

The authors of this paper are all proponents of the MAVT approach to MCDA and collectively have a wide-ranging and extensive experience of its use in practice and of teaching the approach to University students ranging from first year undergraduates to post-experience MBA students.  Approximately 500 MBA students have been introduced to the approach each year (since 1996) and a small survey conducted in 1999 indicated that 30% of respondents went on to use the approach in their future work.  Whilst this experience is testimony to the usability and perceived benefits of the use of MAVT in practice, it also sensitises us to potential difficulties and misunderstandings, one of which is the interpretation and elicitation of weights. 

The meaning of the weights incorporated in multi-attribute value functions is clearly defined; they are scaling factors that specify the relative value decision makers’ attribute to changes in performance on different criteria.  However, despite the well-defined operational meaning and a plethora of procedures to facilitate elicitation of weight values, it is recognised that some decision makers have difficulty in understanding and embracing the concept, preferring to think and communicate in terms of ill-defined notions of importance.   In the context of a decision workshop or a classroom, the MCDA “expert” can be alert for such difficulties and can seek to address them; but that is not the case in the world of e-democracy.

Thus, the Even Swaps Approach, proposed by Hammond, Keeney and Raiffa in 1998, is an interesting alternative to MAVT as it does not utilise criteria weights.  But how is viewed by decision makers?   Over the past 3 years we have carried out a number of studies, involving around 300 MBA students (all of whom have experience as practicing managers and a third of whom are currently employed in managerial jobs), to explore their perceptions of the ease of use and relative strengths and weaknesses of the Even Swaps and MAVT approaches.  In this paper we report on quantitative and qualitative analyses of the data gathered from these studies and reflect on what lessons we might draw from these for the use of MCDA in e-democracy.