What is the best approach for determining where to set the CT threshold when you have >15 samples? Is it best to go through all of them, looking for a range of best fit, and then just choose one value that fits all of them?
The best way to set the threshold is to make sure that your PPC values are between 18 and 22. I would look my first PCR Array, set it so that the PPC is at 20, and see if the same threshold fits for the rest of the arrays.