Table 1

Model	Cluster	θ16	Variance	Incorporation Rate	Number Non-zero Peaks
Bi-Linear	Overall	0.519	0.0084	0.887	75
Single-Cluster	1	0.538	0.064	0.900	7
	2	0.527	0.037	0.878	8
	3	0.515	0.031	0.875	8
	4	0.517	0.035	0.874	8
	5	0.517	0.040	0.881	8
	6	0.548	0.048	0.899	8
	7	0.528	0.068	0.900	7
	8	0.507	0.258	0.900	6
	9	0	NA	0.900	5
	10	0	NA	0.900	5
	11	0	NA	0.900	5

Table 1: Comparison of the performance of the bi-linear model and the singlecluster regression model for a single molecular species that was detected across 11 elution spectra. Clusters are numbered in the order in which they eluted from the LC column. The single-cluster model is that described in Eckel-Passow et al. (2006).