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50 Exhibit 52. Comparisons of Socioeconomic Characteristics of Sample with National Averages. National Group Sample Bias in results? Average Male 49% 45% No, video lab participants mirror national average. Age over 60 16% 29% The video lab oversampled people over 60, which might possibly have a slight positive effect on LOS ratings for the bicycle video clips. Single-family detached dwelling 60% 36% The video lab undersampled people living unit in single-family homes, which might possibly have a slight positive effect on LOS ratings for the pedestrian video clips. Has vehicle available 90% 91% No, video lab participants mirror national average. Source for national averages: US Census, 2000, American Fact Finder, Tables P8, H32, and H44. Station had the highest percentage of participants who never Pilot Tests walked, never biked, and never rode transit. Pilot test sessions, using 14 GMU graduate students, were Validity of Video Lab Respondent Sample held to test the study methodology, to ensure that the surveys were easily understood by the participants, to refine our pres- The selected demographic characteristics of the video lab entation of the materials, and to refine the study materials (such participants were compared with national averages (presented as how many clips to show and needing to increase font size for in Exhibit 52). With the exception of seniors (who were over- older drivers). Pilot test session data will not be included in the sampled) and single-family home residents (who were under- final database, but is available for review in hard copy format. sampled), the video labs generally secured a representative One of the primary goals of the pilot test sessions was to de- national average of participants. termine if the order of video presentation by mode influenced ratings. For example, should the videos be shown in the order Survey Instrument Auto Driver, Bicycle Rider, Pedestrian or in the order Pedes- trian, Bicycle Rider, Auto Driver? To control for the order, Survey instruments were developed to standardize data one order was presented to one study group and the other collection of input from the study participants. Study partic- order was presented to the second study group. It was deter- ipants were asked to rate 10 video clips per mode on a six- mined that order of presentation had a slight influence on point scale (A-F). Study participants were instructed that the participant ratings, in particular for the auto video clips. A to F scale was similar to that used in grade school in which Using this information, the team determined that the videos A was to represent the highest performance and F to repre- needed to be shown in a consistent order at each of the four sent the worst performance. locations to control for potential mode order bias in partici- Pilot tests conducted by GMU in Phase I of NCHRP 3-70 pant ratings. The pilot sessions also revealed that the study revealed that trip purpose (i.e.,leisure versus time-constrained materials were understandable to the participants, but that trips) influenced participant ratings of service quality; as a the font needed to be increased in some cases to account for result, the team decided to focus study participants on time- vision loss in older participants. In addition, some of the constrained trips to better align with procedures in the HCM questions in the demographic survey were rearranged to pro- which are typically focused on peak-hour conditions. Study vide better consistency in terms of those questions that participants were instructed to choose the rating that best rep- required filling in a blank versus circling a response. resented their assessment of quality as a commuter after watching each video clip. Video Lab Sessions A demographic survey instrument was also developed by team members for use in data analysis to better understand Laboratory sessions were held in four locations, as previ- the motivation for responses by groups or individual partic- ously noted. The study locations selected (large hotels in each ipants. The survey contains questions about participant age of the four cities) had access to transit facilities, as well as, group, gender, typical travel mode, and the use of all modes available parking; this provided the participants with easy to (including transit) during a typical day, week, and month. reach locations as well as a sense of security. Two study ses- The survey instruments were developed to be easily under- sions were held in each location to enable older participants stood and easily completed by the participants. Appendix A to attend daytime sessions (to address their desired times of includes the survey instruments created for the study. arrival) and to enable working professionals to attend