Did people "buy" what was "sold"? A qualitative evaluation of a contingent valuation survey information set for gains in life expectancy.

A number of stated preferences studies have estimated a monetary value for the gains in life expectancy resulting from pollution control, using a Value of a Life Year (VOLY) approach. However, life expectancy gains are a complex concept and no attempt has been made, to date, to investigate peoples' understanding of what it is they are being asked to value. Past practice has been to focus on the outcome of a policy i.e. a gain to the average person of X months', providing no details on how the individual receives, or experiences this gain, a potentially important attribute to value. This paper sets up and reports the results from a structured debriefing exercise to qualitatively investigate an alternative approach which explicitly emphasises how this gain is delivered (on-going reductions in the risk of death). We find that, for the majority of respondents, the approach is effective in communicating the on-going nature of the gain and reduces or eliminates the use of the (incorrect) heuristic that it is an 'add-on' at the end of life, in poor health. Further refinements are required, however, to communicate the cumulative nature of these risk reductions and the lack of impact on quality of life. The lesson for stated preference studies in general is that structured debriefings can be very useful, highlighting such issues as the persistence of ill-defined attributes and the difficulties that respondents may encounter setting aside their preferences over attributes of the good that should not be included in the valuation.