Figure 4.

PCA of prominent significant wavenumbers. Plots produced after application of PCA to the panel of significant wavenumbers. (A) Scree plot showing the number of components to retain explaining at least 5% of the variation. The first 3 components explain 95% variance. Scatterplots of the loadings of each cancer (C) and normal (N) sputum spectrum on: (B) components 1 (PC1) and 2 (PC2); (C) components 1 and 3 (PC3); (D) components 2 and 3.