For each measurement (n) I would either add the individual error (if n>mean value) or subtract the individual error (if n<mean value) to have a set of worst case values. I would then calculate the standard error of the mean of the new worst case values. I think this would then account for the error in individual analyses as well as the spread across the 10 measurements. Is this correct? If so, is there a name for this method? If not, why not and what is the correct way to propagate these errors? Thanks ahead of time!