Standard Test Methods for Sewing Threads

Acceptance Testing—The test methods in Test Methods D204 for the determination of the properties of sewing thread are considered satisfactory for acceptance testing of commercial shipments of sewing thread, unless specified in the individual test method. These test methods are the best available and are used extensively in the trade.

If there are differences of practical significance between reported test results for two laboratories (or more) comparative test should be performed to determine if there is a statistical bias between them using competent statistical assistance. As a minimum, use the samples for such a comparative tests that are as homogeneous as possible, drawn from the same lot of material as the samples that resulted in disparate results during initial testing and randomly assigned in equal numbers to each laboratory. The test results from the laboratories involved should be compared using a statistical test for unpaired data, a probability level chosen prior to the testing series. If a bias is found, either its cause must be found and corrected, or future test results for that material must be adjusted in consideration of the known bias.