Round, round, get around ...
Where do we go and how much space do we cover in our daily lives? As we age, mobility, especially within the community, becomes increasingly important to our mental, physical and social health. However, can we observe and quantify this type of neighborhood movement and how does it differ from one individual to another? We tracked 95 Vancouver older adults using Global Positioning Systems (GPS) to map the geographic area that they traverse during a typical week and compared seniors’ mobility patterns.
How do we track where people go?
This study used three main techniques to understand where people go: GPS, travel diaries, and accelerometers. GPS devices (Image 1) use information from satellites orbiting the earth to identify an individual’s location. Travel diaries can fill in gaps in this information including the start and end locations, reason for travel, mode of travel, or companions for each trip. Similarly, an accelerometer measures the level of physical activity and can help to determine whether a GPS track is walking, driving, or using another mode of travel. Older adults wore GPS and accelerometers for seven days while simultaneously reporting in their travel diary. Researchers then processed these data and identified trips older adults took over those seven days.
Measuring “Activity Spaces” from GPS Locations
Once we have the locations and routes that older adults travel throughout their day we can use them to create what are known as “activity spaces.” An activity space is a measure of the spatial behavior of an individual. That is, they measure where someone goes, how much space they cover, and what the general geographic patterns are. For this study we created three different types of activity spaces (Image 2) and measured them based on how big they were (area) and their shape (“compactness”).
How do Activity Spaces compare across different older adults?
Not surprisingly, we found that activity spaces are generally larger for younger participants, as well as those in less walkable neighborhoods, with a valid driver’s license and access to a car. This is likely because people who can drive use their car to extend their geographic range. More interestingly, participants who reported that they had some physical support to go outside also had larger activity spaces. This may show the importance of social engagement and assistance for older adult mobility.
While the shape and size of someone’s geographic extent may give insight into their mobility, questions remain about what destinations are INSIDE that geographic extent. What retail shopping opportunities or services are captured during an older adult’s day? Does having different amenities within one's activity space lead to different levels of physical activity? As a next step for this project we will begin to explore these questions. We will continue to sort out elements that comprise a healthy community and look at what community features may help older adults successfully maintain their mobility.
IMAGE 1: Accelerometers and GPS Device
IMAGE 2: Activity Spaces