Statistical Problems in Calibrating Radiocarbon Dates

The transformation of radiocarbon years to calendar years (cal AD/BC) is not straightforward because of past variations in atmospheric 14 C content (de Vries 1958; Suess 1970). A calibration curve, y = f ( x ), transforms each dendrochronologically dated calendar age ( x ) to a 14 C date ( y ). By inverting this relationship, one can determine the calibrated calendar age of a given sample. In some time intervals, the calibration curve is problematic in that f ( x ) is not uniquely invertible (Fig. 1); even an exact measurement of y cannot be converted to a single calendar age (see examples in van der Plicht & Mook (1987)).