1.1 This practice describes methods for the statistical analysis of laboratory results obtained from interlaboratory proficiency testing programs. As per Practice E 1301, proficiency testing is the use of interlaboratory comparisons for the determination of laboratory testing or measurement performance. Conversely, collaborative study (or collaborative trial) is the use of interlaboratory comparisons for the determination of the performance characteristics of a method, as covered by Practice E 691.

1.1.1 Method A covers testing programs using single test results obtained by testing a single sample (each laboratory submits a single test result).

1.1.2 Method B covers testing programs using paired test results obtained by testing two samples (each laboratory submits one test result for each of the two samples). The two samples should be of the same material or two materials similar enough to have approximately the same degree of variation in test results.

1.2 Methods A and B are applicable to proficiency testing programs containing a minimum of 10 participating laboratories.

1.3 The methods provide direction for assessing and categorizing the performance of individual laboratories based on the relative likelihood of occurrence of their test results, and for determining estimates of testing variation associated with repeatability and reproducibility.

1.4 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.