Quantification of PCR using delta-delta Ct method. - Quantification (Nov/15/2004 )

One of the most used quantification methods in PCR is the "delta-delta Ct" method. In this method we use the Ct-value given from the fixed threshold value and detected product of the PCR-reaction.

To me it seems that the "Ct-value" is a exponetial value. Is this right? Does anyone have any comment on this?

Of course the values are exponential as the PCR reactions are exponential functions..
In the delta-delta ct method usually the expression is normalized against a housekeeping gene, the given difference (delta-ct) is then substracted from the calibrator sample resulting in the delta-delta-ct value.