Fig. 4.
Boxplots describing the quantification cycle (Cq) as a function of laboratory for the 10 samples analyzed in the interlaboratory study. The concentration of samples was individually randomized and blinded for each participant. The circles (●) in the plots represent individual datapoints, with different colors indicating the randomization of the samples. A value of 45 was assigned for undetectable Cq values in order to visualize the generated data. The dashed line indicates the threshold (Cq = 37) used to indicate positive detection. Note that data from laboratory 6 were not included in the statistical analysis because of deviation from the provided protocol.