I have a lot of data collected from the flow cytometer, mainly GFP fluorescence expression data of which I am measuring the fold change when I add a drug however I did not use calibration beads to standardise the values across experiments. Is there a way to convert the raw expression data e.g the mean fluorescence of a population into a standardised value so I can calculate the fold change because it seems that samples that have initially a large amount of fluorescence, the fold change is a lot higher than samples that start off with low fluorescence. Would I have to re-do all the experiments with calibration beads?