Linking GPS and travel diary data using sequence alignment in a study of children's independent mobility

<p>Abstract</p> <p>Background</p> <p>Global positioning systems (<b>GPS</b>) are increasingly being used in health research to determine the location of study participants. Combining GPS data with data collected via travel/activity diaries allows researchers to assess where people travel in conjunction with data about trip purpose and accompaniment. However, linking GPS and diary data is problematic and to date the only method has been to match the two datasets manually, which is time consuming and unlikely to be practical for larger data sets. This paper assesses the feasibility of a new sequence alignment method of linking GPS and travel diary data in comparison with the manual matching method.</p> <p>Methods</p> <p>GPS and travel diary data obtained from a study of children's independent mobility were linked using sequence alignment algorithms to test the proof of concept. Travel diaries were assessed for quality by counting the number of errors and inconsistencies in each participant's set of diaries. The success of the sequence alignment method was compared for higher versus lower quality travel diaries, and for accompanied versus unaccompanied trips. Time taken and percentage of trips matched were compared for the sequence alignment method and the manual method.</p> <p>Results</p> <p>The sequence alignment method matched 61.9% of all trips. Higher quality travel diaries were associated with higher match rates in both the sequence alignment and manual matching methods. The sequence alignment method performed almost as well as the manual method and was an order of magnitude faster. However, the sequence alignment method was less successful at fully matching trips and at matching unaccompanied trips.</p> <p>Conclusions</p> <p>Sequence alignment is a promising method of linking GPS and travel diary data in large population datasets, especially if limitations in the trip detection algorithm are addressed.</p

The incidence of injuries traveling to and from school by travel mode

Objective. To assess the absolute and relative risks of youth school-related travel using the New Zealand's no fault accident liability scheme and Census at School datasets. Methods. Injury risk associated with traveling to and from school was assessed by combining census data from the Accident Compensation Commission database, New Zealand's no fault liability accident scheme database and the Census at School survey. Population injury and cost was assessed for incidents during a 2-year period (1 July 2003 to 30 June 2005) and during normal school travel hours (7.30 a.m.–9.00 a.m., 3.00 p.m.–4.30 p.m., weekdays) for youth 5–17 years of age. Results. Overall, 7573 cases were identified as being school travel-related, representing 1.6% of total, and 11.4% school travel period injuries. Walking (30.7%), cycling (30.3%), and motor vehicles (27.7%) provided the majority of injuries. Risk of injury per million trips was highest for cycling (46.1), walking (10.3), and motor vehicle travel (6.1). Conclusion. These data provide the first comprehensive examination of absolute risk of travel to and from school and by transport mode, showing that school-related travel is a relatively safe activity contributing to a minority of all injuries sustained by youth

Environmental and socio-demographic associates of children's active transport to school: a cross-sectional investigation from the URBAN Study

BACKGROUND: Active transport (e.g., walking, cycling) to school (ATS) can contribute to children's physical activity and health. The built environment is acknowledged as an important factor in understanding children's ATS, alongside parental factors and seasonality. Inconsistencies in methodological approaches exist, and a clear understanding of factors related to ATS remains equivocal. The purpose of this study was to gain a better understanding of associates of children's ATS, by considering the effects of daily weather patterns and neighbourhood walk ability and neighbourhood preferences (i.e., for living in a high or low walkable neighbourhood) on this behaviour. METHODS: Data were drawn from the Understanding Relationships between Activity and Neighbourhoods study, a cross-sectional study of physical activity and the built environment in adults and children in four New Zealand cities. Parents of participating children completed an interview and daily trip diary that assessed their child's mode of travel to school, household and individual demographic information, and parental neighbourhood preference. Daily weather data were downloaded from New Zealand's national climate database. Geographic information systems-derived variables were calculated for distance to school and neighbourhood walkability. Bivariate analyses were conducted with ATS and potential associates; factors related to ATS at p less than 0.20 were considered simultaneously in generalized estimation equation models, and backwards elimination of non-significant factors was conducted; city was treated as a fixed effect in all models. RESULTS: A total of 217 children aged 6.5-15 years participated in this study. Female sex, age, city, household income, limited/no car access, residing in zone of school, shorter distance to school, neighbourhood self selection, rainfall, and sunlight hours were simultaneously considered in multivariate generalised estimation equation modelling (all p less than 0.20 in bivariate analyses). After elimination of non-significant factors, age (p = 0.005), shorter distance to school (p less than 0.001), city (p = 0.03), and neighbourhood self selection (p = 0.04) remained significantly associated with ATS in the multivariate analysis. CONCLUSION: Distance to school is the prevailing environmental influencing factor on children's ATS. This study, in conjunction with previous research, suggests that school siting is likely an important associate of children's ATS

Understanding the Relationship between Activity and Neighbourhoods (URBAN) Study: research design and methodology

<p>Abstract</p> <p>Background</p> <p>Built environment attributes are recognized as being important contributors to physical activity (PA) engagement and body size in adults and children. However, much of the existing research in this emergent public health field is hindered by methodological limitations, including: population and site homogeneity, reliance on self-report measures, aggregated measures of PA, and inadequate statistical modeling. As an integral component of multi-country collaborative research, the Understanding the Relationship between Activity and Neighbourhoods (URBAN) Study seeks to overcome these limitations by determining the strengths of association between detailed measures of the neighborhood built environment with PA levels across multiple domains and body size measures in adults and children. This article outlines the research protocol developed for the URBAN Study.</p> <p>Methods and design</p> <p>The URBAN Study is a multi-centered, stratified, cross-sectional research design, collecting data across four New Zealand cities. Within each city, 12 neighborhoods were identified and selected for investigation based on higher or lower walkability and Māori demographic attributes. Neighborhoods were selected to ensure equal representation of these characteristics. Within each selected neighborhood, 42 households are being randomly selected and an adult and child (where possible) recruited into the study. Data collection includes: objective and self-reported PA engagement, neighborhood perceptions, demographics, and body size measures. The study was designed to recruit approximately 2,000 adults and 250 children into the project. Other aspects of the study include photovoice, which is a qualitative assessment of built environment features associated with PA engagement, an audit of the neighborhood streetscape environment, and an individualized neighborhood walkability profile centered on each participant's residential address. Multilevel modeling will be used to examine the individual-level and neighborhood-level relationships with PA engagement and body size.</p> <p>Discussion</p> <p>The URBAN Study is applying a novel scientifically robust research design to provide urgently needed epidemiological information regarding the associations between the built environment and health outcomes. The findings will contribute to a larger, international initiative in which similar neighborhood selection and PA measurement procedures are utilized across eight countries. Accordingly, this study directly addresses the international priority issues of increasing PA engagement and decreasing obesity levels.</p

Neighbourhood built environment associations with body size in adults:mediating effects of activity and sedentariness in a cross-sectional study of New Zealand adults

Background: The aim of this study was to determine the associations between body size and built environment walkability variables, as well as the mediating role of physical activity and sedentary behaviours with body size. Methods: Objective environment, body size (body mass index (BMI), waist circumference (WC)), and sedentary time and physical activity data were collected from a random selection of 2033 adults aged 20-65 years living in 48 neighbourhoods across four New Zealand cities. Multilevel regression models were calculated for each comparison between body size outcome and built environment exposure. Results and Discussion: Street connectivity and neighborhood destination accessibility were significant predictors of body size (1 SDchange predicted a 1.27 to 1.41 % reduction in BMI and a 1.76 to 2.29 % reduction in WC). Significantrelationships were also observed for streetscape (1 SD change predicted a 1.33 % reduction in BMI) anddwelling density (1 SD change predicted a 1.97 % reduction in BMI). Mediation analyses revealed asignificant mediating effect of physical activity on the relationships between body size and street connectivity and neighbourhood destination accessibility (explaining between 10.4 and 14.6 % of the total effect). No significant mediating effect of sedentary behaviour was found. Findings from this cross-sectional study of a random selection of New Zealand adults are consistent with international research. Findings are limited to individual environment features only; conclusions cannot be drawn about the cumulative and combined effect of individual features on outcomes. Conclusions: Built environment features were associated with body size in the expected directions. Objectively-assessed physical activity mediated observed built environment-body size relationships

Transport-related physical activity, health outcomes, and urban design: descriptive evidence

Environments that support physical activity (PA) engagement are now seen as an important part of the solution for accumulating daily physical activity which confers health benefits, particularly transport-related PA (TPA). Despite this recognition, understanding the determinants of health-related PA has traditionally focused on identifying associations between the social environment and non-specific PA domains. As such, prior to commencing this thesis little was known about the relationships between the built environment and overall PA engagement within the New Zealand context. Little was also known about associations between TPA attitudes and behaviours, and urban design. This research sought to overcome this paucity of knowledge by investigating associations between overall PA and TPA engagement and perceptions, health outcomes, urban design, and socio-demographic variables from a public health perspective. The body of research was initiated with two literature reviews that formed the context for the following six empirical chapters. Data in the empirical chapters were drawn from three self-report surveys using adult samples. The research commenced by examining associations between urban design and overall PA engagement, and then narrowed towards TPA-specific relationships. TPA relationships were identified through the development and implementation of a reliable survey that captured associated behaviours and attitudes. Several new findings were drawn from this body of work. Overall, 21% of adults recognised they could replace automobile journeys on at least two days per week, and walking was deemed an acceptable travel alternative. Adult TPA engagement levels were low; 7% commuted to place of work/study and 32% travelled to the convenience shop by TPA modes. Furthermore, when compared with those who commuted to an occupation by TPA, respondents who used motorised travel were less likely to be classified as active (odds ratio (OR)=0.5) and be of normal body mass index (OR=0.5). No significant health relationships existed for convenience shop travel. As well, 4% of adults reported no automobile availability. When this group was compared with those with unrestricted automobile availability, they were less likely to be classified as active (OR=0.3), but were more likely to engage in TPA modes to access destinations (occupation, OR=6.3; convenience shop, OR=9.8). Occupation-related commute distances also revealed interesting findings. Overall, 50% of respondents perceived they could, and 10% of the sample actually did, commute by TPA modes for distances less than five kilometres, and relationships were strongly mediated by distance. Other urban design variables were objectively assessed with TPA engagement for occupation-related commute distances less than five kilometres. Those who travelled along the most connected street networks were more likely to engage in TPA modes (OR=6.9) when compared with respondents travelling along the least connected networks. No relationships were found with other urban design variables and TPA engagement.This research substantially contributes to this research area by identifying associations between overall PA and TPA engagement and perceptions with urban design. It is likely that shifting the perceptions of adults who recognise they can employ TPA modes, into actual TPA engagement will result in promising population health gains. Future PA initiatives with adults should consider promoting walking for transport as a sustainable solution. A lack of TPA interventions is evident; however, methodological issues need to be resolved before developing such initiatives. Although strategies aimed towards changing perceptions may be valuable for future TPA interventions, it is likely macro-scale urban design modifications (e.g., improved job-housing balance, highly-grained street networks) and legislation (e.g., automobile restrictions) will have the greatest success for increasing TPA engagement in the adult population