How accurate are the test results?

This is not a simple question and cannot be answered in a few words. Testing accuracy or precision must be defined for each parameter measured, and even for the same parameters the accuracy or precision may vary, depending upon the type of request. For example, the measurement precision of Mean Fibre Diameter of fleece samples is at least a factor of two less than that for IWTO Certificates, because fewer sub-samples are tested.

In establishing test methods scientists consider the end-use of the method and the precision required. In the case of Certificates, where the information is used to determine price, a high degree of precision is necessary. However, the precision that can be achieved is also dictated by the cost of the test, and this is also a consideration.

The AWTA Ltd website provides some detailed information on precision and accuracy in the Technical Publications section of the site. The relevant publication can be read on-line or downloaded as an Acrobat file and read off-line. Hard copies can be obtained from any AWTA Ltd Office.