# range of ratios calculated by the pfaffl method? - how to calculate them? (Sep/09/2007 )

Hello,

recently i have switched to the pfaffl method to calculate my gene expression ratios. Currently, i'm wondering how to calculate the range of the ratios obtained by this method.

In case of the ddCt method it is clearly described in ABI's user bulletin #2, page 35. As the ddCt method is more or less a special case (where the E of test and reference samples is the same) of the pfaffl method i have tried to convert it.

Indeed, I'm getting results that look meaningful. Furthermore, for control I have calculated the examples in the ABI user bulletin #2 (page 15) with my method and interestingly my results are always the half of the ones in the brochure. It seems that somehow I have calculated the +/- values. Finally, I have to admit that maths is not my main subject.

here's a short example: instead of 1 (0.9-1.1) i'm getting 1 (0.95-1.05).

So, maybe someone can explain to me how to calculate the range of ratios obtained by the Pfaffl method. I have also looked for literature but I have not really found one that goes into detail about this topic

thanks in advance

Hi!

Sorry, I can't tell you, because I haven't used this so far. I remember reading some paper by Pfaffl about his method but it did not stuck to my head because actually I don't need it

Anyway you checked his homepage? There you find all his papers (http://www.gene-quantification.info/). Sorry, if you allready did.

Cheers!

Jan

Hello,

i just wanted to mention that i have found literature concerning this problem. they are the same formulas used for the qGene applet. maybe it is interesting for somebody.

1: Biotechniques. 2002 Jun;32(6):1372-4, 1376, 1378-9.

Processing of gene expression data generated by quantitative real-time RT-PCR.

Muller PY, Janovjak H, Miserez AR, Dobbie Z.

just register online to get access to biotechniques, its free.