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How to calculate the error (bar), when comparing means of two samples
Posted by: mocrrcn (IP Hidden, New member, 1)
Date: April 21, 2007 08:52AM
Hi, folks:
I have a question regarding to the calculation of means and the error bars for my real-time PCR data. I am comparing the expression levels of a gene X in a sample 1 and a sample 2. In order to do that, I did realtime PCR (quantitive RT-PCR) for the gene X in both samples. I also did the similar quantitive RT-PCR for a housekeeping gene, Y, in both samples as a inner control. So, I have four data groups: 1) X in sample 1 2) X in sample 2 3) Y in sample 1 4) Y in sample 2 For each group, I did the realtime PCR for three times. Therefore, I have three data for each and can calculate the mean and standard deviation. In order to do a relative quantification analysis, I intend to normalize the mean of X in sample 1 to the mean of Y in sample 1 and do the same for the sample 2. My question is how to generate the error bar. Because the final value is a ratio of two means, I don't know how to use my data and/or standard deviations to calculate the error bar. The error bar would supposedly indicate the confidence or precision of this calculation of means. I hope I make this question clear. Thank you in advance for your help and input!
Re: How to calculate the error (bar), when comparing means of two samples
Posted by: mitolab (IP Hidden, Senior member, 89)
Date: April 21, 2007 10:55AM
According to the ABI real-time pcr bulletin, you can use standard deviation of dCt as error bar. I suppose you are doing relative quantification.
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