________________________________________ From: [email protected] [[email protected]] on behalf of TR [[email protected]] Sent: Thursday, December 01, 2011 2:59 AM To: [email protected] Subject: RE: qPCR analysis with error bars
Have a look at this manual: http://www3.appliedbiosystems.com/cms/groups/mcb_support/documents/generaldocuments/cms_042380.pdf Step 6 (pag. 58) has the following title: Incorporating the standard deviation of the ΔΔCT values into the fold difference. _______________________________________________ Yes, I've seen that. Their example problem doesn't contain any biological replicates. Taking biological variation through the calculations is what is confusing me. I also find their "step 5" to be very suspect. "The calculation of ΔΔCT involves subtraction of the ΔCT calibrator value. This is subtraction of an arbitrary constant, so the standard deviation of the ΔΔCT value is the same as the standard deviation of the ΔCT value. Therefore, ΔΔCT Drug Treatment A sample = ΔΔCT = 4.37±0.10 – 6.86±0.17 = –2.5±0.10" 6.86±0.17 sure doesn't look like an arbitrary constant. It looks like a measured value with uncertainty that will affect the outcome of the calculation. _______________________________________________ Methods mailing list [email protected] http://www.bio.net/biomail/listinfo/methods
