BMC Public Health 2007, 7:285 http://www.biomedcentral.com/1471-2458/7/285 bourhood environment. According to Yen and Syme, this research can be divided into studies investigating the roles of (1) the quality of the local environment, (2) the social organisation of the local community, often reflected in social capital and/or social cohesion, and (3) the socio- economic status of the neighbourhood [1]. All three aspects of the neighbourhood environment appear to be associated with community health. Studies focussing on the quality of the local environment have shown that per- ceived neighbourhood problems and crime, the absence of green space, and poor access to amenities are linked with the reporting of poor health [2-10]. The importance of social capital and social cohesion for people's physical and psychological well-being is now well known in the social epidemiological literature [11-13]. Although there is still considerable disagreement about the definition, measure- ment, and workings of social capital and cohesion, vari- ous studies have shown that these complex social constructs are associated with a wide range of health out- comes, such as life-expectancy, mortality rates, and self rated health [14-19]. The group of studies investigating the health effects of community socio-economic status con- sistently report significant associations with a large number of health outcomes, generally showing that peo- ple living in deprived neighbourhoods have poorer health [1,20]. A limitation of many studies investigating the health effects of social and physical aspects of the neighbour- hood environment is that they fail to take into account differences in neighbourhood socio-economic status. The results of these studies are ambiguous considering that disadvantaged neighbourhoods may suffer from poorer physical and social infrastructures, [5] and that there is still a lack of clarity about the specific pathways that link area of residence to health [21]. It may be that, as sug- gested by Stafford and Marmot [22], the association between neighbourhood deprivation and health is medi- ated by perceived neighbourhood and housing problems, or that the associations between specific neighbourhood attributes and health are spurious, and may actually reflect the impact of neighbourhood socio-economic sta- tus. There is some evidence that the place where a person lives may not affect all people in the same way [22-25]. Recent research suggests that the neighbourhood environment is more important for women than for men [26-28]. The social environment appears to be particularly important for women's health status. In contrast, men's health status seems to be more affected by the physical environment and by neighbourhood socio-economic status [28-31]. In this study we examine the importance of different social and physical aspects of the neighbourhood envi- ronment for people's self rated health. We specifically focus on the neighbourhood aspects of access to ameni- ties, neighbourhood quality, neighbourhood disorder, and social cohesion; and investigate whether the possible health effects reflect differences in socio-demographic composition and/or neighbourhood deprivation. We additionally examine whether the associations with differ- ent aspects of the neighbourhood vary between men and women. Methods Population In this study we used population survey data from the Caerphilly Health and Social Needs Study (CHSNS) that were collected in 2001. Caerphilly county borough is sit- uated in south-east Wales, United Kingdom, with an adult population of around 130,000, and is one of five unitary authority local government areas within the former Gwent Health Authority area. The survey sample was drawn from the general practitioner age-sex register held by the former Gwent Health Authority and stratified by census ward. In total, 22,290 questionnaires were distrib- uted. Of these, 12,408 were returned, which equates to a 62.7% response rate after the removal of incorrect addresses. In this study we only use the responses of peo- ple under 75 years of age (n = 10,892), as the individual responses for older respondents are less reliable due to cognitive decline. The response rate for this subgroup was 62.3%. All individual responses were geo-referenced to the 325 census enumeration districts (ED) of Caerphilly borough council. EDs were considered the most appropri- ate geographical unit for this study, as these are the small- est and most homogeneous geographical unit available at the time the work was being carried out. The survey was granted ethical approval by Gwent Local Research Ethics Committee and participant gave implied consent after reading information about the project. A more detailed description of the process of the survey has been given elsewhere [32,33]. Measures Self rated health was used as the outcome variable (see Table 1). Respondents were asked to rate their health on a five-point scale. The scale was dichotomised with 1 repre- senting fair and poor health and 0 representing good, very good or excellent health. The socio-demographics of gender, age, social class, employment status, and household tenure were included as independent variables in the analyses. Age was consid- ered a continuous variable, and centred at the mean of 47.3 years. Social class was measured using the Registrar General's occupation-based classification: I and II (profes- sionals and intermediates), III NM (skilled non-manual), III M (skilled manual), IV and V (partly and unskilled Page 2 of 10 (page number not for citation purposes)