Sir

Scott Campbell and Ellen Townsend's critique (Nature 425, 559; 200310.1038/425559b) of the GM Nation? report makes a big claim: “The methodology was so badly flawed that the data not only failed to support the authors' conclusions, but undermined them”. As a social scientist and a member of the steering board for this debate on genetic modification (I write in a personal capacity), I am unimpressed. They misrepresent the nature of the exercise overall and their critique is flawed.

Campbell and Townsend approach the GM Nation? report (http://www.gmnation.org) as if it were a narrow psychometric study, rather than an account of a multifaceted process of public debate, taking place in real time in a politically contentious field. Owing to this misreading, their analysis is selective and misleading.

For example, in their analysis of data gathered from two of the primary activities involved in this exercise — the nationwide open debates, and the more controlled narrow-but-deep (NBD) focus groups — the authors miss the central point of this twin-track approach. In addition to understanding how far the views expressed by the NBD groups matched those of the inevitably self-selecting participants in the open events, we also wished to follow the evolving views of NBD participants as they acquired more understanding of GM-related issues over a two-week period.

Insights from this exercise contributed towards the steering board's judgements about the likely state of latent, as well as explicitly expressed, public opinion — and to our confidence in the robustness of the key findings.

No one would claim that the GM debate was a flawless exercise, though, like others involved, I regard it as time fruitfully spent. It will be and should be evaluated rigorously, not least for lessons that can be learned for the benefit of similar exercises in the future. The Campbell and Townsend critique is not a helpful contribution in this regard.