STATISTICAL EVALUATION OF THE TESTS
ANNEX IISupplementary provisions
ANNEX II STATISTICAL EVALUATION OF THE TESTS 1. Starting point The starting point for the statistical evaluation of the test results are the following values, calculated for the minimum number of individual test vehicles or tyres: 1. for VTP tests, the value ‘C VTP, ratio ’ calculated in accordance with Article 7, for N = 1; 2. for air drag tests, the value ‘C d A ratio ’ calculated in accordance with Article 10(2), for N = 1; 3. for tyre rolling resistance coefficient tests, the value ‘RRC ratio ’ calculated in accordance with Article 13, for N = 3; 4. for mass tests, the value ‘mass ratio ’ calculated in accordance with Article 16, for N = 3. The granting approval authority shall determine if it is necessary to test additional vehicles or tyres by applying the criteria set out in point 3 of this Annex. 2. Statistical parameters For the total number of vehicles or tyres tested (N), the average (X tests ) and the standard deviation (s) of the test results shall be determined by applying the following formulas: and if N > 2, where: x i is the ratio calculated for the individual test vehicle or tyre i: — C VTP, ratio for VTP test results in accordance with Article 7, — CdA ratio for air drag test results in accordance with Article 10(2), — RRC ratio for tyre rolling resistance coefficient test results in accordance with Article 13, — mass ratio for mass test results in accordance with Article 16. 3. Evaluation After each additional vehicle or tyre tested, the value X tests shall be assessed as set out below in order to reach one of the following conclusions for the vehicle or tyre family concerned: 1. Pass the family if: 2. Fail the family if: 3. Test an additional vehicle or tyre if: where: bound P and bound F are set out in Table 1 of this Annex for VTP test results and for air drag test results; bound P and bound F are set out in Table 2 of this Annex for tyre rolling resistance coefficient test results and for mass test results; s is the standard deviation determined in accordance with point 2 of this Annex; A is 1,03 for VTP test results; A is for air drag test results, where N x is the number of vehicles tested with a date of first registration from 1 July 2027; N y is the number of vehicles tested with a date of first registration before 1 July 2027; A is 1,03 for tyre rolling resistance coefficient test results; A is for mass test results, where N x is the number of vehicles tested with a date of first registration from 1 July 2027; N y is the number of vehicles tested with a date of first registration before 1 July 2027. Table 1 Values for bound P and bound F for VTP test results and for air drag test results Number of vehicles tested bound P bound F 1 A – 0,03 A + 0,07 2 A – 0,03 A + 0,05 3 A – 0,8027 * s A + 0,7325 * s 4 A – 0,3973 * s A + 0,2233 * s 5 A A Table 2 Values for bound P and bound F for tyre rolling resistance coefficient test results and for mass test results Number of vehicles tested bound P bound F 3 A – 2,2655 * s A + max{1,1062, (0,02 / s)} * s 4 A – 1,5093 * s A + 0,5970 * s 5 A – 1,1230 * s A + 0,3737 * s 6 A – 0,8196 * s A + 0,2430 * s 7 A – 0,5944 * s A + 0,1548 * s 8 A – 0,3866 * s A + 0,0902 * s 9 A – 0,1873 * s A + 0,0402 * s 10 A A 4. Calculation of the size of the deviation For the calculation of the size of the deviation, the average ratio is defined as X tests for the total number of vehicles tested, after the vehicle or tyre family has failed according to point 3(2) of this Annex: average ratio = X tests