Application of Student t-test for evaluation of interlaboratory comparative tests results

Abstract

The results of interlaboratory comparative tests typically represent a small sample size. Therefore, to evaluate the quality of test results of laboratories participating in interlaboratory comparative tests, it is proposed to use Student t-test, which connects three main characteristics of small sample: the width of the confidence interval, the corresponding confidence probability and sample size. The examples of interlaboratory comparative tests of diesel show, that the use Student test allows to more objectively evaluate the quality of tests results of laboratories, in particular to identify and assess the results outside the confidence interval of the certified value of the sample for inspection. The calculation of average values of Student statistic for the aggregate test results allows to evaluate the quality of the laboratory, to range them, to form a ranking of laboratories on an objective basis.

Keywords

• межлабораторные сравнительные испытания
• испытательные лаборатории
• оценка результата испытаний
• оценка качества работы лаборатории
• аттестованное значение
• доверительный интервал
• критерий стьюдента
• z-индекс
• interlaboratory comparative tests
• testing laboratories
• evaluation of tests result
• quality assessment of laboratory workflow
• certified value
• confidence interval
• student t-test
• z-index