DIXON test

The AO AC (cited in Ref. [11]) described the precision acceptance criteria at different concentrations within or between days, the details of which are provided in Table 2. Other parameters that should be tested in the precision study are the David-, Dixon- or Grubbs-, and Neumann-tests. The David-test is performed when determining whether the precision data are normally distributed. Outlier testing of the data is performed by the Dixon-test (if n < 6-8) or by the Grubbs-test (if n > 6-8), while trend testing of the data is performed by Neumann-test. Detailed methods have been described in the book written by Kromidas [29]. 

It should be noted that in reviewing the data from the 150, studies, it was found that about 7% of all data reported could be considered outlier data as indicated by a Dixon test. Some international refereed method by experts had to accept up to 10% outliers resulting from best efforts in their analytical laboratories. 

Check for the presence of outliers. If there are suspect values, check by using a statistical test, either the Grubbs or Dixon tests [9]. Do not reject possible outliers just on the basis of statistics. 

In the case of continuous variables, one hitherto used the DIXON test for n < 29 and the GRUBBS test if n > 30. 

Nowadays the DIXON test alone is recommended by standardizing organisations [ISO 5725]. The general formula for the DIXON outlier test is ... 

In this text we refer to the ISO recommended DIXON test, but note that other tests are available, along with tables, in the statistics literature (see, e.g., [MULLER et al., 1979]). 

The evaluation of the distribution of means is performed through a Dixon test (Nalimov). If outlying mean values remain after the technical discussion, it demonstrates that biased results remain and that this technical examination was unreliable. The parameter cannot be certified as a doubt remains on the trueness of the data. 

The search for points called outliers, responsible for a coefficient of variation greater than the fixed value is based on a statistical test (Dixon test). The UV spectra eliminated following this test are considered as not representative of the studied flux. Then, a final statistical test is carried out (Rank test, for example) in order to check if the revealed point is a true isosbestic point. This final test is carried out at X/p 10 nm. 

Diseminated intravascular coagulation (DIG), sepsis induced 997 Dithiothreitol (DTT) 1073 Dixon test 168 DLG2 221... 

The quantity Y (at the points x ) shows a normal distribution (see Fig. 2, left) and is outlier-free (the latter situation is tested with the Dixon test [13], [21] if the assumption is not confirmed, a robust regression method can be used, for example)... 

With the hypothesis and confidence level selected, the next step is to apply the chosen test. For outliers, one test used (perhaps even abused) in analytical chemistry is the Q or Dixon test ... 

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