Figure 6

Processing by SPA-LDA of the ATR-FTIR and Raman spectral datasets for categories: 1983–1984 and 2012–2013.
(A) Four wavenumbers selected by the SPA-LDA model for the ATR-FTIR dataset. (B) Graph representing the power calculation used to identify the optimum number of wavelengths used for SPA. (C) Scores (DF1 × DF2) plot calculated by SPA-LDA. (D) Three wavenumbers selected by SPA-LDA model for the Raman spectral dataset. (E) Graph representing the power calculation used to identify the optimum number of wavelengths to be used for SPA. (F) Scores (DF1 × DF2) plot calculated by SPA-LDA.