FIGURE 1. Metabolite data.

Plots show the distribution of 167 samples of the metabolites etiocholanone and 5 -androstanediol (a, b), and androsterone and 5 -androstanediol (c, d). Panels b and d show samples the French national anti-doping laboratory (LNDD) designate to be 'positive' (red crosses) or 'negative' (green dots); the values from Landis's second sample from stage 17 is shown as a blue dot. Axes display delta notation, expressing isotopic composition of a sample relative to a reference compound.