Characteristics of case and control participants and sites in the risk factor analyses*.

*Matched OR calculated with conditional logistic regression methods. OR denotes odd ratio, and CI confidence interval; NA- OR not calculated because cases/controls were matched by these variables.?For hours/day in school and attends school mostly in pm, and walks to school-7 cases and 7 controls were not attending school at the time of injury; For allowed to play in street- 1 missing control value; For blocks from home to nearest park- 4 missing control values; For absent lane demarcation- 1 missing case value.?High designation corresponds to the highest tertile of all values recorded at all 120 sites (vehicle volume��250 vehicles/hr; vehicle speed��44��7 km.hr, pedestrian volume��201pedestrians/hr).