We next calculated the accuracy of our approach that determines the concentrations of each compound in the mixture. Concentrations form a simplex (i.e. the sum of concentrations for the set is a constant, often normalized to 1), and statistics over the simplex do not follow the same rules as statistics over the unbound R n . Two common approaches to handle compositional data analysis over a simplex are the logratio analysis method and the unit simplex method; in this case the unit simplex method was used for simplicity. For further information on compositional data analysis and these two approaches, we refer the reader to prior reports. Given a D-part composition, the composition vector is given as