Figure 3

One way to characterize the relative lack of variance in m/z (compared to RT) of an isotopic trace is by using an inverse variant of the Theil-Sen estimator--a fully-connected graph is constructed with edges connecting each pair of centroids (circles whose radius indicates abundance), and weighted by the abundance of its connected centroids (represented by line thickness). An isotopic trace will have a weighted average (inverse) slope of approximately zero (not all connections shown).