On the intrinsic accuracy and precision of the standardised growth curve (SGC) and global-SGC (gSGC) methods for equivalent dose determination: A simulation study

In optically stimulated luminescence (OSL) dating, the single aliquot regenerative-dose (SAR) method has been used extensively for determining equivalent doses (De) in quartz. A variation of the SAR method is the “standardised growth curve” (SGC) method, which has been used as an efficient procedure to save measurement time during dating studies. During the application of the SGC method one establishes the SGC and calculation of the De of an aliquot requires only measurement of the standardised natural dose signal. Recently, a “global standardised growth curve” (gSGC) method was developed as an improved version of the SGC procedure. During the application of the gSGC method, the growth curves are re-normalised using sensitivity-corrected signal corresponding to one of the regenerative doses. Subsequently the De of an aliquot is estimated using the sensitivity-corrected natural dose signal and an additional sensitivity-corrected regenerative dose signal as well as the established gSGC. In the present study, simulations are performed to assess the intrinsic accuracy and precision of the SGC and gSGC De estimates. The results of our simulations validate that the gSGC method is intrinsically more precise than the SGC method and is also more accurate for doses greater than 210 Gy. Several factors which affect the reliability of the two methods are investigated.