ASTM D3244 Standard Practice for Utilization of Test Data to Determine Conformance with Specifications
4. Significance and Use
4.1 This practice provides a means whereby the parties to a transaction can resolve potential disputes over those product properties which can be tested and expressed numerically.
4.1.1 This practice can be used to ensure that such properties are correctly stated on labels or in other descriptions of the product.
4.1.2 This practice can be implemented in those cases where a supplier uses a commercial testing laboratory to sample and test a product prior to releasing the product to a shipper (intermediate receiver) and the ultimate receiver also uses a commercial testing laboratory to sample and test the product upon arrival at the destination. The assigned test value (ATV) would still be determined according to 8.3.
4.2 This practice can also assist in the determination of proper tolerances which will ensure that the actual value of a property is sufficiently close to the specification value so that the product is acceptable to the receiver. Such tolerances are bounded by an acceptance limit (AL). If the value determined by testing ( assigned test value, (ATV)) falls on the AL or on the acceptable side of the AL, the product can be accepted; otherwise it must be rejected.
4.3 Both parties must agree in advance on setting the AL and on how the ATV is to be calculated.
4.3.1 This agreement should include a decision as to whether the test values are to be determined by the absolute or rounding-off method of Practice E 29, as therein defined.
4.3.1.1 If the rounding-off method is to be used, the number of significant digits to be retained must also be agreed upon.
4.3.1.2 These decisions must also be made in the case where only one party is involved, as in the case of a label.
4.4 This practice is designed to be suitable for reference in contracts governing the transfer of petroleum products and lubricants from a supplier to a receiver.
4.5 Application of this practice requires the designation of each limit of each property of a specification as "critical" or "noncritical" at a desired probability level, as defined in this practice.
4.6 As a prerequisite for acceptance for lab test results to be used in this practice, the following conditions shall be satisfied:
4.6.1 Long-term standard deviation for the appropriate test method(s) from each lab, as substantiated by in-house quality control programs, on material typical of the product in dispute, shall be statistically equivalent or better than the published method standard deviation under reproducibility conditions.
4.6.2 Each lab shall be able to demonstrate, by way of results from interlaboratory exchange programs, a lack of a statistically significant bias relative to exchange averages for the appropriate test method(s).
4.6.3 In the event that the long-term standard deviation for any party's laboratory is not statistically equivalent, then, for the purpose of establishing the assigned test value (ATV), each laboratory's test result(s) shall be inversely weighted in accordance with laboratory's demonstrated variance(s).
4.7 It is recommended that this practice be conducted under the guidance of a qualified statistician.
