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1、Error and Data Handling 53-5-5. Rejection of A Result Frequently, when a series of replicate analyses are performed, one of the results will appear to differ markedly from the other. A decision will have to be made whether to reject the result or to retain it.2024/9/1421. Q test(1) Arrange the resul
2、ts in order from the lowest to the highest, such as (2) Calculate the difference between the maximum and minimum values (range, R), (3) Find the difference between the questionable result and its nearest neighbor, 2024/9/143(4) The rejection quotient Qc is calculated from the equation;(5) Consult th
3、e table3-3, find the Qt from a table of statistical constants. If , the result can be discarded.If , the result should be retained.2024/9/144Example 1测定水中砷的含量，测定水中砷的含量，3次测定结果分别为次测定结果分别为1mg/L, 2mg/L, 9mg/L.问可疑数据问可疑数据“9”应否弃去应否弃去(P=0.90)?查表3-3得 因 故9mg/L这一数值不应弃去 Critical values for the Rejection Quotien
4、t, Q值表2024/9/145Example 2The following set of chloride analyses on separate aliquots of a pooled serum were reported. One value appears suspect. Determine if it can be ascribed to accidental error. 103, 106, 107, 114meq/liter.SolutionThe suspected number may not be rejected2024/9/1462.G (Grubbs) tes
5、t Calculate the mean of the results and the standard deviation s Calculate the Gcvalue Consult the table, find the Gt Arrange the result from the lowest to the highest(correspond to certain confidence level)2024/9/147If GcCt, the result can be discarded.If GcCt, the result should be retained.In Grubbs test, not only set up certain confidence level, But also introduce the mean and standard deviation, so its accuracy is better than of Q test.2024/9/148有一组测定值为有一组测定值为73.5, 69.5, 69.0, 69.5, 67.0, 67.0, 63.5, 69.5, 70.0, 70.5。问可疑值问可疑值63.5是否应该舍去？置信度是否应该舍去？置信度95%。解：解：解：解：63.5不应舍弃不应舍弃2024/9/149
