15. Report
15.1 Report ratings below 100 octane number to the nearest integer. When the calculated result ends with exactly 0.5, round to the nearest even number; for example, report 91.50 as 92, not 91.
15.1.1 Convert octane number to performance number, if required, using Table A2.1.
15.2 Report ratings above 100 octane number in units of mL TEL per U.S. gallon rounded to the nearest 0.01 mL TEL/gal.
15.2.1 Convert mL TEL per U.S. gallon in isooctane ratings to performance numbers, if required, using Table A2.2.
16. Precision and Bias
16.1 Precision:
16.1.1 Repeatability - In the range from 1.25 mL to 2.00 mL TEL/U.S. gal (129.6 to 138.4 performance number), the difference between two test results obtained by the same operator with the same engine under constant operating conditions on identical test specimens within the same day would, in the long run, in the normal and correct operation of the test method, exceed 0.145 mL TEL/U.S. gal in only one case in 20. Since the relationship between mL TEL/U.S. gal and performance number is not linear, representative repeatability statistics in units of performance number are tabulated in Table 5.
16.1.2 Reproducibility - In the range from 1.25 mL to 2.00 mL TEL/U.S. gal (129.6 to 138.4 performance number), the difference between two single and independent test results obtained by different operators in different laboratories on identical test specimens would, in the long run, in the normal and correct operation of the test method, exceed the value of R in only one case in 20, where R is defined by the equation:
where:
x = the average of the two test results in mL TEL/U.S. gal.
16.1.2.1 The reproducibility values in Table 5 exemplify the values of R over the applicable range. Since reproducibility varies with level and the relationship between mL TEL and performance number is not linear, reproducibility limits in units of performance number are also tabulated in Table 5.
16.1.3 Interlaboratory Test Program - The above precision statements are based on test results obtained by the ASTM Aviation National Exchange Group from 1988 to 1998. During this period, four aviation gasoline samples having supercharge ratings in the range from 1.25 mL to 2.00 mL TEL/U.S. gal were tested each year by 15 to 23 participating laboratories. A report of the data and analysis used to establish the precision statements is available as a research report.
16.1.4 Precision Below 1.25 mL TEL/U.S. Gal and Above 2.00 mL TEL/U.S. Gal - There is not sufficient data to establish the precision of this test method for samples having supercharge ratings below 1.25 mL TEL/U.S. gal or above 2.00 mL TEL/U.S. gal.
16.2 Bias - This test method has no bias because the supercharge rating of aviation gasoline is defined only in terms of this test method.