Optically Stimulated Luminescence (OSL) dating.

<p>Radial plot of the equivalent dose (D<sub>e</sub>) values obtained from 49 individual grains of quartz from sample JQ200-OSL1. Filled circles denote the 46 values used to calculate the weighted mean D<sub>e</sub> for OSL age determination, and open triangles are the three values identified as outliers (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068061#pone-0068061-t001" target="_blank">Table 1</a>). Each point represents the D<sub>e</sub> value for a single grain. It can be read off the radial axis by extending a line from zero on the ‘standardised estimate’ axis through the point of interest, and the ‘relative error’ on this D<sub>e</sub> can be read by projecting a vertical line to intersect the horizontal axis. The ‘precision’ is the reciprocal of the relative error, so the most precise D<sub>e</sub> estimates lie furthest to the right. The grey band is centred on the weighted mean D<sub>e</sub> estimated using the Central Age Model. Individual D<sub>e</sub> values that are consistent at 2σ with this weighted mean fall within the grey band. This D<sub>e</sub> distribution is overdispersed by 23±4%, which is typical for well-bleached samples of quartz that have not been disturbed since burial. See Galbraith and Roberts <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068061#pone.0068061-Galbraith2" target="_blank">[71]</a> for further explanation of statistical aspects of D<sub>e</sub> estimation and display in OSL dating.</p>