10. Precision and Bias
10.1 Precision—The coefficient of variation of test results has been observed to be dependent on the strength level of the beams. The single operator coefficient of variation has been found to be 5.7 %. Therefore, results of two properly conducted tests by the same operator on beams made from the same batch sample are not expected to differ from each other by more than 16 %. The multilaboratory coefficient of variation has been found to be 7.0 %. Therefore, results of two different laboratories on beams made from the same batch sample are not expected to differ from each other by more than 19 %.3