1.1 This practice is used to determine whether the differences between two sets of test results (from tests conducted on material assumed to be the same) are statistically significant or reasonable based on common causes attributed to the test method. 1.2 The paired t-test is used to determine whether there are statistical significant differences in the test results. 1.3 The within-laboratory precision (r) is used to determine whether the differences are reasonable and attributable to common causes by the same operator in the same laboratory using the same equipment. 1.4 The between-laboratory precision (R) is used to determine whether the differences are reasonable and attributable to common causes created by different operators using different equipment, possibly in different laboratories. 1.5 The practice first determines whether there is a statistically significant difference in test results. Statistically significant differences are then checked for reasonableness by comparison to the appropriate test precision, within-laboratory (r), or between-laboratory (R) to determine whether the significantly significant difference is actually a result of small sample size n 20 and known testing variability. 1.6 The practice can be used to determine if single factors change in the test procedure such conditioning time result in statistically significant or reasonable differences. 1.7 Units-The system of units for this practice is not specified. Dimensional quantities in the practice are presented only as examples. 1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
This practice will be used by researchers, government agencies, and in quality control testing to determine the reasonableness of test result differences and determine the effect of changes in test procedures such as sample conditioning.
Keywordsstatistical analysis of test differences; precision and bias; reasonableness of test differences
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top