Relative and radiometric dating
The slope of the line determines the date, and the closeness of fit is a measure of the statistical reliability of the resulting date.
Technical details on how these dates are calculated are given in Radiometric dating. As with any experimental procedure in any field of science, these measurements are subject to certain "glitches" and "anomalies," as noted in the literature.
Absolute dating is a method of estimating the age of a rock sample in years…
Contamination from outside, or the loss of isotopes at any time from the rock's original formation, would change the result.