Use standard observing techniques measures to assure that helmeted and unhelmeted bicyclist are counted the same way. There are two different observation methods. Another method, developed by the Maryland Department of Health and Hygiene and Johns Hopkins University, uses pairs of trained observers placed along bicycling routes selected because they are popular with bicyclists. Other Types of Surveys Besides observational surveys, there are two other types of surveys that can be used to measure helmet wearing. In a classroom survey, a teacher or volunteer asks students if they bicycled to school and if they wore helmets.
Telephone surveys are another method.
A home is called and a number of questions is asked about healthy behavior, including helmet use. Because telephone surveys usually cover an entire area's population, analysis of the telephone survey data can produce area-wide estimates of helmet use. The most common survey is the BRFS - Behavioral Risk Factor Survey, conducted in many U.S. states. Observational surveys are more expensive than telephone surveys. They require trained observers, detailed sample site selection, and a good deal of planning.