*a genuine chronological gradient?*

Although the spread of measurements is relatively small, it is sufficient to cast doubt on the homogeneity of the three laboratories’ samples, and justifies Riani and Atkinson’s claim of the probability of a genuine chronological gradient across the samples (although their conclusions were based on an analysis of all twelve results, not just the three averages above.(Regression Analysis with Partially Labelled Regressors: Carbon Dating of the Shroud of Turin, Riani et al., Statistics and Computing, 2012)

To my way of thinking this plays into the mended shroud explanations for errors in the carbon dating and some image-caused-by-radiation theories current in some circles.