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Table 1 Statistical identification of outliers on data set 3. Data set 3 comprised of three samples X, Y, and Z. Each sample consisted of 18 replicates of known analyte concentration. The table lists the response values (Ct) associated with these 18 replicates per sample, as well as indicating which values appeared to be potential outliers according to the box and whisker plots. For each sample, the Grubbs' test statistic is computed, as well as the classification and recommendations according to ISO guidelines.

From: Standardisation of data from real-time quantitative PCR methods – evaluation of outliers and comparison of calibration curves

 

Sample

 

X

Y

Z

 

24.24

24.41

22.97

 

23.97

27.21

22.93

 

24.44

27.02

22.95

 

24.79

26.81

23.12

 

23.92

26.64

23.59

 

24.53

27.63

23.37

 

24.95

28.42

24.17

 

24.76

25.16

23.48

 

25.18

28.53

23.80

 

25.14

28.06

23.43

 

24.57

27.77

23.66

 

24.49

28.74

28.79

 

24.68

28.35

23.77

 

24.45

28.80

23.98

 

24.48

27.99

23.56

 

24.30

28.21

22.80

 

24.60

28.00

23.29

 

24.57

28.21

23.86

Potential outlier value

23.92

24.41

28.79

Grubbs' test statistic

1.89

2.63

3.83

Outlying value classification

Non significant

Straggler

Outlier

Recommendations

Accept

Accept

Reject