# real time PCR data analysis - method I have never heard of before (Dec/19/2007 )

Hi there,

Does anyone use this formula to calculate expression of gene of interest relative to HK gene:

-2(avCtHK - avCtGOI). It looks like a 'reverse' delta Ct to me, but is it valid enough to use for real time analysis?

Thank you in advance.

the formula is 2^[Ct(reference)-Ct(target)]

this method (=dCt) is a variation of the ddCt method but only normalized to the reference and not to a calibrator. you get essentially the same results like in ddCt eg. you get normalized ratios like 2 and 6 and with the ddCt you would get 1 and 3.

Thank you very much for your reply.

In the formula that I was shown (and calculations I saw) delta Ct was multiplied by two, which doesn't make much sense to me. May be I am missing something...

The method I have seen is 2^-(delta,deltaCt) I have uploaded a statistical reference for the derivation of the method which I use.

Livak and Schmittgen 2001 in Methods.