Fig. 4

P-values of Wilcoxon rank sum test. Results of a two sided Wilcoxon rank sum test (alpha = 0.05) for each wavelength between normal and tumor measurements. The grey wavelength ranges indicate that over these wavelengths there is a significant difference between normal and tumor. The vertical dashed lines represent the wavelengths with the lowest p-value in each grey area. The eight selected wavelengths were: 501 nm, 916 nm, 973 nm, 1145 nm, 1211 nm, 1371 nm, 1424 nm, and 1597 nm