Normalizing qPCR data - (Feb/05/2013 )

I have a question about normalizing qPCR data, specifically calculating the SD (of sample replicates) for normalized data. I run a standard curve with each qPCR run and determine the mean copy number for each sample run in triplicate. To normalize my data I divide the mean copy number of my target gene by the mean copy number of my reference gene (GAPDH, actin, 18s rRNA, etc) - Mean Target Copy/Mean Reference Copy = Normalized Data. I also calculate my SD from the copy number replicates for each sample.

But then how do I calculate the SD for the normalized data? Divide my target SD by the reference gene mean? Should the normalized SD represent the SD of both target and reference?

Thanks

I think that if you just use the upper and lower SD of the target and divide by /mean ref copy number, it should be OK. I don't think the SD of the reference plays a role in this, but I'm no statistician by any means.