Data Collection Strategies
Statewide surveys vary in methodology and frequency of observation. However, all except Wyoming are based upon direct observation of safety belt use. (Wyoming's data are based upon accident reports.) Because the surveys are generally based on a large number of observations from representative sites, they provide a reasonable estimate of seat belt use.
In 1994 NHTSA conducted the National Occupant Protection Use Survey. For the moving traffic study, which provides information on overall shoulder belt use, pairs of observers were stationed for 30 minutes at exit ramps, intersections with stop signs or stop lights and uncontrolled intersections. One observer counted belt use for the drivers of passenger cars and light trucks (vans, minivans, sport utility vehicles and pickup trucks). The second observer counted belt use for the right front passengers. Every day of the week and all daylight hours were covered by the study. Approximately 4,000 locations were selected and a total of more than 167,000 passenger cars and almost 84,000 light trucks were observed.