I am trying to figure out how configure raw data to be expressed as ratios of controls. I want to do this because my experiments utilize fluorescense and the signal intensity can vary from time to time.
To be specific, I entered raw data for my controls and three concentrations of drug. Sample size is 4 for each group. For the control group my mean is 254, SD 2.88, and the SEM is 1.66. For one concentration of drug, the mean value is 278, SD 5.5, and the SEM is 3.18.
I imagine the ratio of drug to control is 1.32 but how do I express the SEM or SD? Variance divided by the mean of the control or mean of the drug?
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