The goal of the 2012 National Survey of Bicyclist and Pedestrian Attitudes and Behavior (NSBPAB) was to obtain a “snapshot” of the attitudes and behaviors with regards to bicycling and pedestrian activities of the U.S. population using a telephone survey of respondents aged 16 years and older. The previous administration of the NSBPAB was conducted in 2002. Only surveys based on probability samples can be used to create mathematically sound statistical inferences about a larger target population. Most statistical formulas for specifying the sampling precision (estimates of sampling variance), given particular sample sizes, are premised on simple random sampling. However, random sampling requires an enumeration of all of the elements in the population. Since no enumeration of the total population of the United States (or its subdivisions) is available, all surveys of the general public are based upon complex sample designs that may employ stratification and two or more stages of sampling. A sampling design using geographic stratification (NHTSA Region), an oversample of young drivers, sampling frames of households with landlines and cell phones, together with an overall sample size of 7,500 was developed and implemented for this survey. The final sample consisted of 7,509 respondents, which included an oversample of 508 participants ages 16-39, with 35.6 percent of respondents coming from cell phone only or cell phone mostly households. Weights were developed to yield national estimates of the target population within specified limits of expected sampling variability. This report describes the methods of sample construction and survey administration, and shows the sample dispositions for each of the three samples and computation of weights. (Author/publisher)
Samenvatting