By Peter Burgess - 11 July 2013

One of the issues facing governments and industry in general is how to persuade people to change their habits to what is believed to be a more desirable situation. Topics relating to food consumption include choosing a healthier diet and living in a more 'sustainable' manner. Recently, for example, concerns about cod stocks led to an organised campaign to promote the consumption of similar species of white fish as an alternative to cod.

Intervention studies are a way of investigating whether a particular method of persuasion is having the desired (or any) effect. In these studies one or several groups of people are exposed to specific factors (also called activities or interventions, which constitute an intervention program), for a certain length of time, and in a specific geographic setting, to see how their beliefs, attitudes and/or behaviours are affected. This type of study is not easy to set up – there may be many confounding factors that have to be taken into consideration.

To ensure that the study outcomes, whether conclusive or not, are exploitable, they have to be designed with much consideration. Reliability and validity are the most important criteria a study should satisfy.

A reliable measurement is one that, if repeated, will give the same results as it did the first time. In surveys or questionnaires, reliability problems often occur when respondents do not understand the questions they are asked, and/or they are asked about something that they do not clearly recall or is of little relevance to them.

Validity refers to data that are not only reliable, but also true and accurate. External validity is particularly relevant to intervention studies. It refers to the extent to which the results of a study can be generalized to other settings or groups. In intervention studies, if results cannot be extrapolated to comparable situations, then they are probably of limited value.

From our previous research, we have developed in–depth knowledge and understanding regarding consumers' concerns and barriers in purchasing products with specific ethical and environmental benefits, as well as products that benefits people's health and well–being. Cost, awareness and knowledge relating to the social and environmental benefits and perceived value of the product benefits all appear to influence consumers' food choices.

We are currently building on this knowledge with an intervention study on the consumption of frozen fish. In this we are looking at the different effects of the level of intervention (the 'soft touch' approach versus a more intense interaction with the consumer), as well as methods of data collection – on–line questionnaires, food diaries, on–line forums and discussion groups. This will enable us to advise on and devise intervention activities for other situations, as well as how to assess the effects.