ISO International Standard

Petroleum and related products — Precision of measurement methods and results — Part 5: Statistical assessment of agreement between two different measurement methods that claim to measure the same property

This document specifies statistical methodology for assessing the expected agreement between two test methods that purport to measure the same property of a material, and for deciding if a simple linear bias correction can further improve the expected agreement.

This document is applicable for analytical methods which measure quantitative properties of petroleum or petroleum products resulting from a multi-sample-multi-lab study (MSMLS). These types of studies include but are not limited to interlaboratory studies (ILS) meeting the requirements of ISO 42591 or equivalent, and proficiency testing programmes (PTP) meeting the requirements of ISO 42593 or equivalent.

The methodology specified in this document establishes the limiting value for the difference between two results where each result is obtained by a different operator using different apparatus and two methods X and Y, respectively, on identical material. One of the methods (X or Y) has been appropriately bias-corrected to agree with the other in accordance with this practice. This limit is designated as the between-methods reproducibility. This value is expected to be exceeded with a probability of 5 % under the correct and normal operation of both test methods due to random variation.

NOTE      Further conditions for application of this methodology are given in 5.1 and 5.2.

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