Figure 4.

Illustration of relation between threshold level, C_q value and C_q variability. The graph shows the amplification curves of triplicate measurements of a 5-step, 10-fold dilution series. Quantification thresholds (dotted green lines) were placed at six levels between the ground phase noise and the plateau phase. For each of the amplification curves the C_q value was determined. The graph in the inset shows the 95% confidence interval of the observed C_q values (mean +/− 2 × SD per dilution). The orange dotted line illustrates that when the threshold is set above the exponential phase, the C_q values are higher than expected. The blue dots are the C_q values determined from the SDM (see Section 6.2). The graph is based on actual amplification data.