Figure 2.

Sensitivity of IsoI measures to various cluster degradations. Left side: degradations are a high level of random intermingling, lower level of intermingling, expansion, and contraction. Scatter-plots of the clusters in the same 2-D projections after the various degradations of C1 are shown in a-d. Voltage in units of mV. Right side: IsoI values before (circle) and after (triangle) degradation. Square in a,b shows IsoI value for the additional new cluster (color coded). Faint gray arrows pointing downward emphasize where decreases in IsoI values occur. a. Random 50% reassignment produces substantial decrease in IsoI values for the 2 derived clusters. Note that oscillatory behavior about the exact value, e.g., 0 for C1′s new IsoI_NN here, during convergence is a general property of the nearest neighbor divergence estimator¹⁶. b. Approximate bisection of cluster C1 within a 2-D feature slice also reduces IsoI values, despite the clear border between derived clusters. c. Expansion: C1 is brought closer to C2,C3, so IsoI values of C2,C3 also decrease. C3, nearest-neighbor to C1, shows large decrease in IsoI_NN. C4,C5 are also slightly degraded. d. Contraction primarily degrades C1 IsoI_BG due to poor isolation from points that are now part of background.