Amplification efficiency determination based on the log-linear region using a six cycle window. Log of the fluorescence readings within the lower region of the five amplification profiles presented in Figure 1A are plotted again cycle number, revealing a large log-linear region within all five profiles. The slope of this line provides an exponential-based estimate of amplification efficiency (Eloglin, equation 5) as summarized in the numerical inlay. The percentages listed below each data point show the predicted cycle efficiency derived from LRE analysis (equation 3). This predicts that a large loss in amplification efficiency occurs within the log-linear region.