Frequency distribution for quantification of maize NK603. Exemplary frequency distribution taken from the dynamic Excel spreadsheet developed in this study. Isolated genomic DNA from certified reference material for maize event NK603 (0.1% [w/w]) was quantified with the novel statistical approach (Figure 1). Figure 2 shows the frequency distribution for automatic setting of baseline and threshold and for 2× 2 replicates (i.e. four randomly chosen copy numbers for transgene were analysed with four randomly chosen copy numbers for reference gene). Columns represent the number of values in the corresponding class (represented by the upper limit given on the horizontal axis). The blue diamond marks the nominal GMO content of the reference material. The corresponding Gaussian normal distribution is shown as brown line. All classes that reach the cut-off (dashed horizontal line) contribute together to at least 95% of all values (green columns; here 96.8%, i.e. 4839/5000). Statistical parameters are shown below the graph: on the left for the values of the entire population ([rel.] StdDevP: [relative] standard deviation of the population; relative |Deviation|: absolute difference average minus nominal value divided by nominal value; SkewnessP: skewness of the population; ChiSq. Norm.Distr.: simplified χ2 test for Gaussian normal distribution with 5% level of significance), on the right for the classes within the cut-off (middle class: upper limit of last included class plus upper limit of first included class divided by 2; ±: range from upper limit of last included class to upper limit of first included class divided by 2).