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33 a p p e n D i x a In Chapter 2 and Chapter 4, figures depicting comparisons between study recruitment areas, their respective states, and the nation as a whole include a series labeled âRecruitment Site Counties Weighted by Nominal Site Size.â Data in these series are weighted based on each siteâs size, as determined by the number of DAS kits nominally allocated to that site, as outlined in Table A.1. Similarly, figures in Chapter 4 that compare the SHRP 2 NDS sample and other relevant populations include a series labeled âSHRP 2 Sample Weighted According to Age/Genderâ derived by weighting the data associated with the study sample accord- ing to the distribution of licensed drivers across the United States in 2012, the last full year of data collection. The weighting factors used to derive this series are presented in Table A.2. Weighting Factors Table A.1. Weighting Factor for Each Site Based on Original Nominal Number of DAS Kits Managed Site No. of DAS Kits Site SizeâBased Weighting Factor New York 450 3 Florida 450 3 Washington 450 3 North Carolina 300 2 Indiana 150 1 Pennsylvania 150 1
34 Table A.2. Weighting Factors for SHRP 2 Sample by Age and Gender Gender Age No. of Licensed Drivers in 2012a 2012 Licensed Drivers Weighting Factor for Age and Gender M â¤19 4,506,199 0.0212742 F â¤19 4,323,609 0.0204122 M 20â24 8,836,224 0.0417167 F 20â24 8,644,805 0.0408130 M 25â29 9,142,229 0.0431614 F 25â29 9,214,424 0.0435023 M 30â34 9,088,323 0.0429069 F 30â34 9,242,363 0.0436342 M 35â39 8,667,787 0.0409215 F 35â39 8,758,112 0.0413480 M 40â44 9,532,858 0.0450056 F 40â44 9,568,468 0.0451737 M 45â49 9,893,354 0.0467076 F 45â49 9,943,257 0.0469432 M 50â54 10,298,601 0.0486208 F 50â54 10,459,435 0.0493801 M 55â59 9,503,385 0.0448665 F 55â59 9,738,712 0.0459775 M 60â64 8,128,957 0.0383777 F 60â64 8,379,398 0.0395600 M 65â69 6,311,060 0.0297952 F 65â69 6,515,908 0.0307623 M 70â74 4,349,210 0.0205331 F 70â74 4,557,392 0.0215159 M 75â79 3,040,690 0.0143554 F 75â79 3,255,371 0.0153689 M 80â84 2,096,580 0.0098982 F 80â84 2,338,480 0.0110402 M 85+ 1,589,660 0.0075050 F 85+ 1,889,979 0.0089228 a Federal Highway Administration 2014.