Statement of Purpose Examine conventional versus innovative approaches to measuring environmental exposures posing violence risks during adolescents’ daily activities.

Methods/approach Using data from a case-control study of daily activities and assault injury among 283 10–24 years old males in Philadelphia, we compared participants’ exposure to 27 environmental risk factors using three Methods home address-based measurement (kernel density (KD)/inverse distance weighting (IDW)), minute-by-minute GIS activity path-based measurement (KD/IDW), and measured differences between actual and potential shortest trip paths (60 ft/660 ft buffers). First, we used R-squared to quantify the extent to which home address-based measures explained gold standard activity path-based measurement. Next, we divided participant’s activity paths into origin-destination segments and used intercept-only linear regressions to test for differences in environmental exposures along actual versus shortest potential trip paths.

Results Defining environmental exposures based on participant home address resulted in significant misclassification compared to activity path measures, with home address-based measures only partially explaining exposures (R-squared range: 0.05–0.81). Additionally, we found that participants’ actual trip paths often differed from shortest potential trip paths, and resulted in statistically significant differences in exposure to vandalism, narcotics arrests, disorderly conduct, public drunkenness, alcohol outlets, and vacant properties (p<0.05).

Conclusions Defining environmental exposures based on participant home address fails to fully account for individual variability in exposure levels accrued over daily activity. Participants often selected trip paths that differed from the shortest potential trip paths, resulting in statistically significant differences in calculated exposures.

Significance/Contribution to Injury and Violence Prevention Science Selecting among different methods for ascribing environmental risk factors to measure participants’ experiences can yield different exposure estimates, and impair our ability to accurately assess associations between environmental exposures and violence. Future research on how environments relate to injury outcomes can utilise the innovative spatial methods explored herein to measure exposures more accurately for a given hypothesis.