From 2014 to 2018, with the support of participating laboratories, Labthink organized 5 times of proficiency service (tensile properties tests were included in 2017).

In the past 4 times of proficiency service, permeability results are based on analysis of Z-score statistics. The results of tensile properties in 2017 were analyzed with Cochran method and Grubbs method, which are usually used in statistical analysis of outliers. Results from previous events are as follow:

It can be concluded from the data comparison results that the uniformity of the permeability test data between laboratories are still needed to be improved. The laboratory operators need to establish a monitoring system of testing data and handle with the problems that exist in the laboratories regularly to guarantee the accuracy of testing data.

As for tensile property data, we can see that even for the same test item, the test results submitted by different laboratories show a great variation and that’s why we need push forward the uniformity of test data of laboratories.