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53 This appendix describes the approach used to estimate the number of persons saved by safety belts (which is used to calcu- late UPFC), number of occupants involved in potentially fatal A P P E N D I X A Calculations of Lives Saved, Number Involved in Fatal Crashes, and Overall Effectiveness of Safety Belts Against Deaths in 2005 Restraint Used Restraint Not Used Total with Known Use Involvement by Vehicle Type Cars # 9,361 8,889 18250 59.3% % 51.3% 48.7% 100% LTVs # 4,578 7,966 12,105 40.7% % 36.5% 63.5% 100% Totals # 13,940 16,854 29,162 100% % 45.3% 54.7% 100% Note: Unknowns Distributed Among Used and Not Used Categories. Vehicle & Seating # Killed # Used Not Used E Effect Est. # Saved Est. # Involved % of Total Overall Effect Car/Front 16,588 8,727 7,861 0.45 7,140 23,728 .519 .233 Car/Rear 1,662 635 1,027 .044 499 2,161 .047 .021 LTV/Front 11,301 4,222 7,079 0.60 6,333 17,634 .386 .231 LTV/Rear 1,243 356 887 0.73 964 2,207 .048 .035 Totals 30,794 13,940 16,854 n/a 14,629 44,917 n/a .521 A B C D E F G H Step 2: Lives Saved (by Vehicle Type and Seating Position) and Overall Effectiveness Notes: Data in Columns A, B, and C are from 2005 FARS file; Estimates in Column D (effectiveness of safety belts against deaths) are from Kahane (2004); Number (of lives) Saved (Column E) = (Column B * Column E)/(1 â Column E); calculated for each combination of vehicle type and seating position. Number Involved (Column F) = Column B (# Used) + Column C (# Not Used) + Column E (# Saved). Percent of Total (occupants involved; for each combination) = Number Involved (in each row of Column F) divided by bottom cell of Column F; H (overall effect) = Sum of products of Column D multiplied by Column G (.521 shown in bottom cell of Column H) crashes, and overall effectiveness of safety belts, given distribu- tion of those involved by vehicle type and by seating position. Deaths coded as âotherâ vehicle were omitted. Step 1: Usage by Vehicle Type
Step 3: Calculating UPFC: Overall, and by Vehicle Type and Seating Position Notes: Data in Columns A, B, and C are from 2005 FARS file; Estimates in Column D (effectiveness of safety belts against deaths) are from Kahane (2004). Number (of lives) Saved (Column E) = (Column B * Column E)/(1 â Column E); calculated for each combination of vehicle type and seating position. Number Involved (Column F) = Column B (# Used) + Column C (# Not Used) + Column E (# Saved). Percent of Total (occupants involved; for each vehicle/seating combination) = Number Involved (in each cell of Column F) divided by bottom cell of Column F. UPFC for each Vehicle/Seating Combination shown in Column H = (Column B + Column E) divided by (Column B + Column C + Column E). Overall UPFC = Sum of products of Column G multiplied by Column H, for each vehicle type and seating position (.631 shown in bottom cell of Column H). 54 Vehicle/ Seating # Killed # Used Not Used (E) Effect # Saved # Involved % of Total UPFC Car/Fr 16,588 8,727 7,861 0.45 7,140 23,728 .519 .669 Car/R 1,662 635 1,027 .044 499 2,161 .047 .525 LTV/Fr 11,301 4,222 7,079 0.60 6,333 17,634 .386 .599 LTV/R 1,243 356 887 0.73 964 2,207 .048 .598 Totals 30,794 13,940 16,854 n/a 14,629 44,917 n/a .631 A B C D E F G H