Day: September 16, 2011

An Extensible Simulation Environment and Movement Metrics for Testing Walking Behavior in Agent-based Models

/ Matt Artz

Computers, Environment and Urban SystemsComputers, Environment and Urban Systems, Available online 6 August 2011

Paul M. Torrens, Atsushi Nara, Xun Li, Haojie Zhu, William A. Griffin, and Scott B. Brown

“Highlights:

  • We present a novel framework for simulating pedestrians and metrics for evaluating movement.
  • Our approach can be applied across application scenarios, cities, and scales.
  • We prove its usefulness in studying a range of movement scenarios at different scales.

“Human movement is a significant ingredient of many social, environmental, and technical systems, yet the importance of movement is often discounted in considering systems’ complexity. Movement is commonly abstracted in agent-based modeling (which is perhaps the methodological vehicle for modeling complex systems), despite the influence of movement upon information exchange and adaptation in a system. In particular, agent-based models of urban pedestrians often treat movement in proxy form at the expense of faithfully treating movement behavior with realistic agency. There exists little consensus about which method is appropriate for representing movement in agent-based schemes. In this paper, we examine popularly-used methods to drive movement in agent-based models, first by introducing a methodology that can flexibly handle many representations of movement at many different scales and second, introducing a suite of tools to benchmark agent movement between models and against real-world trajectory data. We find that most popular movement schemes do a relatively poor job of representing movement, but that some schemes may well be “good enough” for some applications. We also discuss potential avenues for improving the representation of movement in agent-based frameworks.”

Neighborhood Food Environment and Body Mass Index among Japanese Older Adults: Results from the Aichi Gerontological Evaluation Study (AGES)

/ Matt Artz

International Journal of Health GeographicsInternational Journal of Health Geographics, 2011, 10:43

Tomoya Hanibuchi1, Katsunori Kondo, Tomoki Nakaya, Miyo Nakade, Toshiyuki Ojima, Hiroshi Hirai, and Ichiro Kawachi

“Background: The majority of studies of the local food environment in relation to obesity risk have been conducted in the US, UK, and Australia. The evidence remains limited to western societies. The aim of this paper is to examine the association of local food environment to body mass index (BMI) in a study of older Japanese individuals.

“Methods: The analysis was based on 12,595 respondents from cross-sectional data of the Aichi Gerontological Evaluation Study (AGES), conducted in 2006 and 2007. Using Geographic Information Systems (GIS), we mapped respondents’ access to supermarkets, convenience stores, and fast food outlets, based on a street network (both the distance to the nearest stores and the number of stores within 500 m of the respondents’ home). Multiple linear regression and logistic regression analyses were performed to examine the association between food environment and BMI.

“Results: In contrast to previous reports, we found that better access to supermarkets was related to higher BMI. Better access to fast food outlets or convenience stores was also associated with higher BMI, but only among those living alone. The logistic regression analysis, using categorized BMI, showed that the access to supermarkets was only related to being overweight or obese, but not related to being underweight.

“Conclusions: Our findings provide mixed support for the types of food environment measures previously used in western settings. Importantly, our results suggest the need to develop culture-specific approaches to characterizing neighborhood contexts when hypotheses are extrapolated across national borders.”