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 4259-1 or equivalent, and proficiency testing programmes (PTP) meeting the requirements of ISO 4259-3 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.<\/p>\n
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| 2<\/td>\n | undefined <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 5.1 General requirements <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | 5.2 Additional requirements for PTP data 5.2.1 General conditions 5.2.2 Test on existence of extreme samples <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 5.2.3 Test on distribution of lab results <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | 5.2.4 Comparison of precision 5.3 Brief sequential steps of the procedure <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | 5.4 Flow diagram of the procedure <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | 6.1 Sample mean and standard error 6.1.1 General 6.1.2 Computation of the means 6.1.3 Calculation of standard errors <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | 6.2 Suitability of the data 6.2.1 Test on property variation 6.2.2 Correlation of the test methods <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | 6.3 Bias correction selection statistics 6.3.1 General 6.3.2 Class 0\u2014No bias correction 6.3.3 Class 1a\u2014Constant bias correction <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | 6.3.4 Class 1b \u2014 Proportional bias correction 6.3.5 Class 2 \u2014 Proportional and constant bias correction <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | 6.4 Selection of the appropriate bias correction class <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | 6.5 Confirming the normal distribution of weighted residuals <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | 6.6 Sample-specific biases <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Petroleum and related products. Precision of measurement methods and results – Statistical assessment of agreement between two different measurement methods that claim to measure the same property<\/b><\/p>\n |