Methods: Measuring physical activity in public open space — an electronic device versus direct observation

Abstract

Objective: To evaluate the practicality and validity of using infra-red beam counters (IRBCs) to measure walking path use and overall park use.

Monitoring Physical Activity: Uses and Measurement Issues With Automated Counters

“…Further, user volume assessed by the infrared beam ranged from 20% under-estimation to 16% over-estimation. 15 This wide range of inaccuracy may be attributed to the inconsistency of the infrared counter in measurement-double counts, false counts, and an inability to distinguish between individuals can lead to overestimation; while simultaneous passage of two or more people, time-delay activation, and monitor placement (both height and location, as well as multiple entry points) can lead to underestimation. 15,23,30 Based on these results, infrared beams appear to be unreliable and inappropriate for measuring physical activity in outdoor, open areas, and areas with multiple entry points, like parks.…”

“…23,26,30 Three studies found that active infrared counters were particularly vulnerable to errors when used in outdoor settings. 15,23,30 One 4-month study reported that the counter "represented a systematic 15% undercount of trail users." 30 Another study comparing infrared beam counters and direct observation of walking path and overall park use found the infrared beam over-estimated the number of people using the walking path by 14-78% and underestimated park use by 0-69%.…”

“…To date, there has been very little use of automated monitoring for physical activity promotion and surveillance. 15,24,25 Categories of Automated Monitoring:…”

“…Vandalism is another concern. 15,19,20 Active infrared counters can be programmed to minimize false counts from certain objects (e.g., falling leaves) so that the beam must be blocked for a certain amount of time to register a count, and there is a timedelay before the next count can be detected (eliminating double counting). 19 As with seismic devices, using a time-delay increases the risk of missing other people passing through the measurement zone during that time period.…”

“…10,14 In order to effectively and accurately assess the importance and use of environmental resources for physical activity, as well as to evaluate the impact of interventions, rigorous, standardized research methods and valid and reliable measures are required. 10,15 Macro-level approaches to physical activity promotion and surveillance require automated methods of measuring physical activity in the built and natural environments, including stairwells, walking trails, parks and recreation areas, sidewalks, and cycling lanes. Automated counting or monitoring refers to an objective measurement device that can, at minimum, provide automated counts of passages through a specified area (e.g., number of passages of pedestrians or bicyclists at a point on a trail).…”