Statistical approaches used to assess the equity of access to food outlets: a systematic review

Abstract: Background Inequalities in eating behaviours are often linked to the types of food retailers accessible in neighbourhood environments. Numerous studies have aimed to identify if access to healthy and unhealthy food retailers is socioeconomically patterned across neighbourhoods, and thus a potential risk factor for dietary inequalities. Existing reviews have examined differences between methodologies, particularly focussing on neighbourhood and food outlet access measure definitions. However, no review has informatively discussed the suitability of the statistical methodologies employed; a key issue determining the validity of study findings. Our aim was to examine the suitability of statistical approaches adopted in these analyses.
Methods: Searches were conducted for articles published from 2000–2014. Eligible studies included objective measures of the neighbourhood food environment and neighbourhood-level socio-economic status, with a statistical analysis of the association between food outlet access and socio-economic status.
Results Fifty four papers were included. Outlet accessibility was typically defined as the distance to the nearest outlet from the neighbourhood centroid, or as the numberof food outlets within a neighbourhood (or buffer). To assess if these measures were linked to neighbourhood disadvantage, common statistical methods included ANOVA, correlation, and Poisson or negative binomial regression. Although all studies involved spatial data, few considered spatial analysis techniques or spatial autocorrelation.
Conclusions: With advances in GIS software, sophisticated measures of neighbourhood outlet accessibility can be considered. However, approaches to statistical analysis often appear less sophisticated. Care should be taken to consider assumptions underlying the analysis and the possibility of spatially correlated residuals which could affect the results.

Large unburnt areas, not small unburnt patches, are needed to conserve avian diversity in fire-prone landscapes

Mitigating the impacts of large-scale fires on biodiversity is becoming increasingly important as their frequency increases. In response, fire managers have engaged with the concept that retaining small unburnt residual areas of vegetation within extensively burnt landscapes may facilitate biodiversity conservation. However, it remains uncertain how the size and isolation of these unburnt residuals influence faunal distributions, persistence and recovery following fire. We used a replicated observation study to test bird responses to the size and isolation of unburnt residuals in a mallee woodland area recently burnt by a 28 000 ha wildfire in southern Australia. The scale of our study provided a rare opportunity to consider the responses of large mobile organisms to fire-induced habitat fragmentation. Within five replicated spatial blocks, we crossed two levels of isolation with large (5-7 ha) and small (1-3 ha) unburnt patches and matrix sites burnt 5 years previously. We compared these site types to six continuous (non-fragmented) unburnt sites. We surveyed each site on eight occasions. Most birds occurred more frequently in unburnt habitat beyond the extent of the fire. Bird responses to the availability and spatial distribution of unburnt remnants within the fire were largely influenced by their ability to use the recently burnt matrix. Occurrence of five species was higher in unburnt residuals when more of the landscape within 500 m was burnt. A fire refuge effect may be likely for two competitive species that occurred more frequently in unburnt residuals than in the burnt matrix or continuous unburnt habitat. For the weebill, recolonization following fire was likely to occur gradually over time from ex situ sources. Synthesis and applications. To maintain avian diversity in fire-prone landscapes, our results suggest a need to shift management focus from creating networks of small unburnt patches towards preserving large, intact areas of habitat. However, five species common to the burnt matrix preferentially selected residual patches when unburnt resources were locally scarce. Therefore, to benefit birds, land managers should limit the extent of applied burns and use narrow burns. When planning large burns, practitioners should consider that a number of species will remain absent from the landscape for several decades.

Cultural adaptation and validation of the Health Literacy Questionnaire (HLQ): robust nine-dimension Danish language confirmatory factor model

Health literacy is an important construct in population health and healthcare requiring rigorous measurement. The Health Literacy Questionnaire (HLQ), with nine scales, measures a broad perception of health literacy. This study aimed to adapt the HLQ to the Danish setting, and to examine the factor structure, homogeneity, reliability and discriminant validity. The HLQ was adapted using forward-backward translation, consensus conference and cognitive interviews (n = 15). Psychometric properties were examined based on data collected by face-to-face interview (n = 481). Tests included difficulty level, composite scale reliability and confirmatory factor analysis (CFA). Cognitive testing revealed that only minor re-wording was required. The easiest scale to respond to positively was 'Social support for health', and the hardest were 'Navigating the healthcare system' and 'Appraisal of health information'. CFA of the individual scales showed acceptably high loadings (range 0.49-0.93). CFA fit statistics after including correlated residuals were good for seven scales, acceptable for one. Composite reliability and Cronbach's α were >0.8 for all but one scale. A nine-factor CFA model was fitted to items with no cross-loadings or correlated residuals allowed. Given this restricted model, the fit was satisfactory. The HLQ appears robust for its intended application of assessing health literacy in a range of settings. Further work is required to demonstrate sensitivity to measure changes.