P-value for degradation end time vs. R_I for total edge intensity (o) and directional edge intensity (+).

Note the differences between total and directional edge intensity methods. While both methods show significance (p<0.05) over a large range of R_I, the total edge intensity is statistically different over almost the entire regime [.19, .81], while directional edge intensity is statistically different over the range from [.12, .53].