Hoddinott et al. BMC Public Health 2010, 10:800 http://www.biomedcentral.com/1471-2458/10/800 Table 1 The setting A) Within the meeting place and venue - the activity setting B) The immediate surrounding environment including parallel activity settings C) The wider geographical area For each of the above consider: ○ Socio-demographic characteristics, facilities, human and structural resources (e.g. funds, time, people, physical objects) ○ Access issues ○ Sensory aspects (comfort, temperature, noise, smell, visual) ○ Meanings attributed to the setting including opportunities and threats D) The wider policy, political, media, legal, cultural and environmental context and how it interacts with the group compared to the predominant approach of measuring the psychological variables of individuals receiving a behaviour change intervention. Theorising interventions as events in complex systems is particularly relevant to health improvement groups, where the context, the change in relationships and resources over time are important [31]. The importance of the behavioural set- ting [32] or the activity setting [33] as a unit of analysis is a cross disciplinary feature of psychological, social and biological ecology [32,34]. Behavioural or activity set- tings refer to time and space bounded patterns of beha- viour, and the concept originates from research which characterised all behaviour settings in a small American community [32]. This demonstrated that behavioural settings have effects on individuals that extend beyond the specific behaviour demanded by the activity. It can be helpful to consider the context in which the group intervention takes place at macro, meso and micro levels, as proposed in ecological models of health improvement [35]. The macro level considers how wider policy, economic and socio-cultural factors interact with the group, for example media scares or the cultural values of participants. The meso level includes the inter- relations between the group, the setting and the sur- rounding environment, for example holding the group in an affluent or disadvantaged area can influence per- ceptions and who attends a group [18]. Importantly, the impact of parallel activity settings [33] which may target the same population should be considered. For example, the impact that general parent craft groups open to all women can have on participation in breastfeeding only groups [18]. Similarly, consideration should be given to assessing the impact of activities displaced by the group intervention [31]. What providers and participants stop doing when a health improvement group starts is likely to be crucial to outcomes, yet this is seldom systemati- cally described or evaluated. The micro level is the interaction between group participants and the space where the group meets. Community settings like church halls or family centres convey different meanings for people compared to health settings and health service Page 4 of 9 group leaders may behave differently outside health service settings [18]. Group resources can vary between purposely designed venues with state of the art props to “make do” multi-purpose clinically cluttered spaces. Consideration should also be given to sensory percep- tions including comfort, temperature, noise, smell and visual appearance [20]. Designing a group intervention Table 2 focuses on the design of the intervention, the theory underlying the choice of intervention, the target population and choosing the relevant behavioural out- come to measure. What is the intervention and what quantity will be delivered? The interactions between group members may form the intervention as with peer support or self-care [7]. The intervention might be something which is delivered by the group leader, like a particular diet or exercise pro- gramme and there may be a range of intended and actual interaction between group participants from minimal, mainly non-verbal communication to high level engagement. The intervention may intend to have an outreach beyond the group setting, for example sex education delivered by peer educators [36]. It is particu- larly important in trials of interventions in group set- tings to consider the statistical aspects of whether the group attributes and processes detailed in Tables 1, 2 and 3 are acting as mediators or moderators between the intervention and the health outcomes. The group size, frequency, duration and lifetime will all influence group composition and processes. Decisions about the components of the intervention are linked to the under- lying theory informing it and the outcomes of interest which are discussed below. There are detailed guidelines about how to report the attributes of complex interven- tions which are relevant to groups [37,38]. However, reducing complex social processes like groups into stan- dardised, reproducible intervention components has its critics [39] and interventions which are responsive to local contexts and change over time may be more appropriate. How does someone become a group member? It is important to assess how entry rituals and gate- keeper assumptions are influencing information dissemi- nation and recruitment to a group. Some groups have elaborate entry rituals, for example general practitioners may be asked to complete forms prior to registering for a cardiac rehabilitation group whereas other groups encourage open access. Convenience, minimising bar- riers and ensuring that the participant benefits outweigh the risks are crucial to a successful group and will be highly context dependent [20]. In a study comparing commercial and health service groups for weight loss,