Fractionation dating method
Due to variability in sample homogeneity, sample collection, and sample processing, the variability of replicate samples (reproducibility) is generally greater than the reported error for a single sample.
A total measurement error can be estimated by adding in quadrature the reported error with this extra variability, or added variance.
Fraction Modern is a measurement of the deviation of the C is also affected by natural isotopic fractionation.At NOSAMS, added variance is determined by pooling differences of measurements of secondary standards from consensus values of those standards.For calendar year 2016, the estimated added variance for samples of the process type OC (Organic Carbon) or HY (Hydrolysis) is 2.6‰ for samples containing Reporting of ages and/or activities follows the convention outlined by Stuiver and Polach (1977) and Stuiver (1980).The final reported error is the larger of the internal or external error, propagated with errors from the normalizing standards and blank subtraction.
It should be noted that the reported error is an estimate of the precision (repeatability) of measurement for a single sample.
One other situation that limits the age (if not already limited by the background age) is the error of the AMS result.