BMC Public Health 2009, 9:207 http://www.biomedcentral.com/1471-2458/9/207 insight into reasons for non-involvement. As the projects have different target groups, differences by age, gender and ethnicity will be captured. The project participants identified in each area will be followed-up in interviews in years 2 and 3. This will occur whether the individual is still participating in the project or not. In addition, informa- tion from project providers regarding the content, intended outcomes and participation in the three project themes within each area will be gathered. Such an approach will allow differences in perception and experi- ence to come through by person, broad project theme and area. This sampling strategy will allow analysis by project, person and place. Topic guides will be developed for both sets of interviews and are derived from the conceptual framework discussed above. These may be modified between the waves of inter- views to reflect emerging issues. Data will be analyzed using thematic content analysis and a longitudinal within-subject analysis to examine changes over time. As well as producing important conclusions in themselves, qualitative findings will later be integrated with results from the quantitative survey instruments and the process evaluation, including the community-level variables and information on variance in intervention delivery. This will allow a more detailed assessment of how mode of delivery and local contexts may modulate the effectiveness of spe- cific components of the intervention activities and will, in turn, inform the evaluation of their replicability and of the likely effectiveness in other contexts. Study of Structural and Ecological characteristics The evaluation takes account of considerable evidence that health and health behaviours are influenced by the social and physical environment (SPE) [8] Interventions to promote health need to act on, and take account of the wider influence of health-promoting and health-endan- gering characteristics of communities and places. For example, the effectiveness of interventions to promote physical activity is determined not just by how well or how intensively the intervention is implemented, but also by the context – including the physical environment (for example, the availability of green and open spaces) and the social environment (for example, levels of crime; and subjective perceptions of how safe the local area is to walk in). Similarly, the effectiveness of interventions to pro- mote mental health and wellbeing has been shown to be influenced not just by mental health at baseline, but also by a wider range of social determinants such as the quality of urban environments [60]; transport services [61] and social and employment networks, as well as many other characteristics of neighbourhoods. The Well London activities, will act directly on the SPE characteristics of intervention areas as well as on individ- ual health behaviours and it is therefore necessary to measure changes over the course of the study in SPE at community level as a complement to both the individual- level trial outcome indicators and the qualitative study of individuals interacting within their local contexts. The study will collect and analyse data on the health related quality of SPE, the range of local amenities, facilities and services, community engagement (CE) and social net- works at different timepoints before during and after intervention delivery. These data will be collected in four ways. First we use routine data to construct indicators of health promoting or endangering SPE characteristics of the Well London LSOAs. This data is drawn from databases held by the GLA, The London Health Observatory, LAs and PCTs along with commercial databases, Transport for London and the Metropolitan Police and other sources. Well Lon- don already has established relationships with these organizations and has access to much of the data they hold at LSOA level and above. This will allow us to pro- vide initial maps of these indicators in both the control and intervention areas; to characterise the relationship between the environment and health at baseline, and in some cases to assess change in these indicators over time. Secondly, the delivery of the Well London programme itself provides an important source of qualitative informa- tion on community level indicators. The initial CE process has mapped existing amenities and facilities and aspects of SPE which impact health and health behaviour in order to design interventions that complement existing ameni- ties and facilities, fill in gaps in provision and leverage resources to priority areas. Thirdly, questions on individuals' perceptions of the qual- ity, accessibility and acceptability of the SPE, on the qual- ity of local amenities and services, on CE and social networks are included in the adult survey questionnaire and are an objective of the qualitative longitudinal study. Finally we will carry out additional primary fieldwork to collect information about the SPE not available through the ways already described. This includes information on the control areas that has not been automatically gener- ated through the Well London design process. A checklist of SPE factors which might influence health will be com- piled, together with careful delineation of theoretical causal pathways, using evidence from the literature and CE findings. These will include factors influencing HE (such as differential access to different types of food, dis- tance to shops and exposure to advertising [62,63]), HPA and MH (such as walkability, distance to parks, neigh- bourhood aesthetics, environmental quality and safety, and access to structured exercise and good quality hous- Page 8 of 11 (page number not for citation purposes)