What is the difference between 2nd derivative and primary curve?
The 2nd derivative and primary curve are two ways to determine a cycle threshold value. If the primary curve is used the cycle threshold reported is the intersection of the growth curve and the threshold. If the 2nd derivative is selected the software determines the cycle threshold value by calculating the 2nd derivative of the growth curve. The software chooses the largest 2nd derivative peak for the cycle threshold (this is usually the inflection point of the growth curve).
